Plant Science 2

Jump to each topic by clicking on the relevant box below

What is an adaptation? A feature that has evolved in a species to improve its survival within its particular habitat

What is totipotency? The potential of a cell to differentiate into any type of specialised cell. In leaves this means the potential for cells not normally found in leaves to be produced, such as root cells.

Creates buoyancy in the leaves of aquatic plants meaning the leaves float. This maximises their photosynthetic potential vs. leaves under water.
Storage of water in photosynthetic regions, allowing the plant to survive periods with dry soil.
Often pungent to reduce incidence of herbivory, but also have a role in reducing water loss from the leaf.
Reduces potential for water to be lost through leaf surfaces; also improves shedding of water during heavy rain.
Reduces airflow around the stomata and traps humid air; the shape reduces leaf surface area, limiting potential leaf heating in hot weather.
Structures that part or fully cover leaves. Higher coverage increasingly reduces airflow around a leaf, trapping air which becomes humid so transpiration is reduced.
Storage of water and carbohydrates in an underground structure. This reduces access to the plant from herbivores and buffers it from extremes of temperature.
The lower surface area of each leaf reduces potential for transpiration.

Answers: A - 6 B - 4 C - 5 D - 8 E - 2 F - 3 G - 1 H - 7

Match the leaf adaptation to the description:

(Match letter to number)

A. Hairy leaves

B. Waxy leaves

C. Rolled leaves

D. Reduced leaves

E. Succulent leaves

F. Leaf oils

G. Aerenchyma cells in leaf

H. Bulbs

What is the scientific term for a hairy leaf?
What is the scientific name for an individual leaf hair?

What is a benefit of leaf hairs to wildlife?

Leaf hairs can aid in reducing water loss from leaves. What are the other benefits of leaf hairs?

A dense covering of leaf hairs reflects light, reducing leaf heating in hot weather. This is an advantage in reducing the rate of transpiration and therefore water loss from the leaf.
A dense covering of leaf hairs traps fungal spores, reducing the potential for pathogen attack on/in the leaf.
In some species, such as Urtica dioica, leaf hairs contain an irritant chemical to deter herbivory.
Some species, such as Galium aparine, have hooked leaf hairs that enable it to climb upward and position its leaves in an optimum position for photosynthesis.

State the disadvantages of leaf hairs

A dense covering of leaf hairs reflects light, reducing potential for photosynthesis.
Leaf hairs can trap light-blocking particles such as pollen and dust, reducing light entry to the leaf and therefore limiting photosynthesis.
Producing leaf hairs is an energetic expense to the plant.
Hirsute leaves trap water. This can be a disadvantage in the wet UK autumn and winters where likelihood of fungal infection is higher.

The waxy cuticle is produced by the epidermis
The waxy cuticle is only produced on the upper surface of leaves
The waxy cuticle improves the absorption of rain drops into the leaf
The waxy cuticle reduces water loss from inside a leaf
Pathogens are less likely to gain entry to a leaf that has a thick waxy cuticle
Evergreen plants from wet climates and succulent plants from dry climates both produce a thick waxy cuticle
In a compost heap, evergreen leaves with a thick waxy cuticle tend to break down as quickly as deciduous leaves
Leaves with a thick waxy cuticle have a matt appearance

Answers: 1. True 2. False - the epidermis covers all surfaces of a leaf (and wider plant), therefore both the upper and lower leaf surfaces have a waxy cuticle. 3. False. The waxy cuticle is hydrophobic, meaning water cannot pass through it. Therefore raindrops do not pass through it and cannot be absorbed into the epidermal layer. 4. True 5. True 6. True. 7. False. The thick waxy cuticle is a barrier to detritivores and decomposers, reducing the relative rate of leaf decomposition. 8. False. They have a glossy/shiny appearance.

Decide if the statements below are true or false:

Define the term xerophytic Xerophytic plants are adapted to survive in dry conditions, such as arid habitats or as epiphytes or lithophytes. They typically have succulent leaves and/or stems.

How are this plant's leaves adapted for an arid habitat? - There is a thick waxy cuticle which prevents water loss from inside the leaf. - The leaves are succulent, meaning they store water, enabling plants to survive when the soil is dry.

What types of garden situations would best suit a hardy plant with succulent leaves?

Why are succulent plants preferable for summer container displays vs. plants that do not have succulence?

Plants with succulent leaves can survive periods with dry roots, which can occur in dry weather in containers. This means they don't need such regular irrigation as non-succulent plants, reducing their water footprint. They also have a slower growth rate, meaning a lower potential need for fertiliser. The production of fertiliser has a high carbon footprint so using succulent plants vs. non-succulent, faster growing plants reduces the potential carbon footprint of the container display.

The pine needles pictured above are an example of rolled foliage.

1. Explain the advantages of rolled leaves.

2. Explain the disadvantages of rolled leaves.

3. The pine needles have a relatively glossy/shiny surface. What causes this?

4. Classify this plant in terms of its lifecycle.

1. Explain the advantages of rolled leaves.

Rolled leaves have their lower surface on the inside, meaning stomata are not exposed to wind. This allows high humidity to build around stomata, reducing transpiration. This allows the plant to better survive in dry conditions.

2. Explain the disadvantages of rolled leaves.

Rolled leaves do not have their entire lamina exposed to maximum light. This reduces their photosynthetic potential, meaning less carbohydrate is produced than non-rolled leaves. This results in a slower potential growth rate than non-rolled leaved plants, which is a competitive disadvantage.

3. The pine needles have a relatively glossy/shiny surface. What causes this?

Pine needles have a thick waxy cuticle

4. Classify this plant in terms of its lifecycle.

This is a woody perennial (the photo does not show if it's a tree or a shrub so neither can be applied in this instance)

The plant pictured above is Lavandula angustifolia (lavender). It has reduced leaves.

1. Explain the advantages of reduced leaves.

2. Explain the disadvantages of reduced leaves.

3. Lavender foliage is fragrant when rubbed. Why is this and what's the advantage to the plant?

4. What are the advantages and disadvantages of lavender's glaucous foliage?

1. Explain the advantages of reduced leaves.

They have a lower surface area, which reduces transpiration from each leaf, enabling a plant to better survive periods of dry soil.

2. Explain the disadvantages of reduced leaves.

The reduced surface area of each leaf means each leaf has a lower photosynthetic potential than broader leaves. This results in a potential compatitive disadvantage in garden situations.

3. Lavender foliage is fragrant when rubbed. Why is this and what's the advantage to the plant?

Lavender has pungent oils in its leaf. These both help to reduce water loss and deter herbivores. Reduced herbivory, such as from aphids, means lower potential for the spread of pathogens.

4. What are the advantages and disadvantages of lavender's glaucous foliage?

Advantages: the pale colour reflects light, reducing leaf heating in hot weather. This means less water loss from the leaf as well as less heat stress. This allows the plant to better withstand hot weather.

Disadvantages: due its reflective qualities, less light enters the leaf, reducing potential for photosynthesis and carbohydrate production. This results in a relatively slower growth rate than an equivalent green leaved plant.

An onion has been cut in half and is pictured.

What is the overall adapted structure seen in an onions, tulips and daffodils called?
What is the function of the structure named in Q1?
What botanical structures indicated with the letter A on the photo forms the edible part of an onion?
Name the structure overlaid by the letter B
What is the function of structure B?
What is the function of the papery outer layers of an onion?
What types of roots does an onion produce?

1. What is the overall adapted structure seen in an onions, tulips and daffodils called?

A bulb

2. What is the function of the structure named in Q1?

Bulbs store water and carbohydrates (energy)

3. What botanical structures indicated with the letter A on the photo forms the edible part of an onion?

Leaves (succulent leaves)

4. Name the structure overlaid by the letter B

Basal plate

5. What is the function of structure B?

Produces new succulent leaves and new photosynthetic leaves, inflorescences, roots

6. What is the function of the papery outer layers of an onion?

Protects the bulb from entry of pests and pathogens

7. What types of roots does an onion produce?

Fibrous roots

Typically purchased in the autumn
Most are recommended to be planted three times their depth
Tend to be taller growing
Excellent for providing nectar and pollen to pollinators when few other plants are in flower
Do not need to be watered in if planted in the ground
Have tap roots
All are monocotyledonous
Are adapted for dry summer weather
Commonly propagated via tissue culture
Are almost invariably planted amongst/between other plants, rather than forming a planted area of their own

Answers: 1. Spring flowering bulbs 2. Both 3. Summer flowering bulbs 4. Spring flowering bulbs 5. Both 6. Summer flowering bulbs 7. Neither 8. Spring flowering bulbs (they go dormant in summer, e.g. in the dry shade under deciduous trees) 9. Both (this is almost always the case for cultivars) 10. Spring flowering bulbs (some summer flowering bulbs like Crinum spp. or Eucomis spp. can be planted as a clump but spring flowering bulbs are dormant in summer and leave a gap)

Decide if the statements below apply to spring flowering bulbs, summer flowering bulbs, both or neither:

Each number relates to a specific word, so if you think (1)________ is 'bananas' then if (1)________ appears later on in the passage, 'bananas' is the missing word.

Coloured leaves:

Plants with coloured leaves are usually shades of (1) p________, (2) y________ or (3) g________-g________.

Plants with (1) p________ leaves have higher levels of (4)__________, which absorbs yellow and green wavelengths of (5)________, making leaves appear (1) p________. Theorised advantages include (1) p________ leaves being less attractive to (6) h________, and the absorption of (7)________ light by (4)__________, reducing potential damage to the leaf. Plants with (1) p________ leaves are naturally occurring but are also selected by plant breeders and sold as named (8)________ (clones).

Plants with (2) y________ leaves have (9)________ concentrations of chlorophyll, resulting in the (2) y________ hue. This results in an overall lower rate of (10)________ in leaves, meaning less carbohydrate is produced. Therefore (2) y________ leaved plants have a (11)________ growth rate. In nature plants with (2) y________ leaves are typically (12)________ by neighbouring green leaved plants, meaning they do not persist in the wild. Therefore (2) y________ leaved plants almost always naturally arise as a result of a (13)________, rather than an inherited trait.

Plants with (3) g________-g________ leaves typically come from (14)________ climates, such as Mediterranean climates, deserts and (14)________ alpine/mountainous habitats. Their colouration (15)________ excess sunlight, limiting excessive leaf heating in hot weather. This reduces (16) t________ and heat stress, meaning the plant is better (17)________ for survival in its natural habitat.

Coloured leaves:

Plants with coloured leaves are usually shades of (1) purple, (2) yellow or (3) grey-green.

Plants with (1) purple leaves have higher levels of (4) anthocyanin, which absorbs yellow and green wavelengths of (5) light, making leaves appear (1) purple. Theorised advantages include (1) purple leaves being less attractive to (6) herbivores, and the absorption of (7) UV / ultraviolet light by (4)anthocyanin, reducing potential damage to the leaf. Plants with (1) purple leaves are naturally occurring but are also selected by plant breeders and sold as named (8) cultivars (clones).

Plants with (2) yellow leaves have (9) lower concentrations of chlorophyll, resulting in the (2) yellow hue. This results in an overall lower rate of (10) photosynthesis in leaves, meaning less carbohydrate is produced. Therefore (2) yellow leaved plants have a (11) slower growth rate. In nature plants with (2) yellow leaves are typically (12) outcompeted by neighbouring green leaved plants, meaning they do not persist in the wild. Therefore (2) yellow leaved plants almost always naturally arise as a result of a (13) mutation, rather than an inherited trait.

Plants with (3) grey-green leaves typically come from (14) sunny climates, such as Mediterranean climates, deserts and (14) sunny alpine/mountainous habitats. Their colouration (15) reflects excess sunlight, limiting excessive leaf heating in hot weather. This reduces (16) transpiration and heat stress, meaning the plant is better (17) adapted for survival in its natural habitat.

Hint: the missing words in a random order UV / ultraviolet, reflects, yellow, lower, herbivores, adapted, purple, slower, mutation, sunny, anthocyanin, grey-green, transpiration, outcompeted, photosynthesis, cultivars, outcompeted

Extra Hint: (1) purple

Extra Hint: (2) yellow

Extra Hint: (3) grey-green

Extra Hint: (4) anthocyanin

Extra Hint: (5) light

Extra Hint: (6) herbivores

Extra Hint: (7) UV / ultraviolet

Extra Hint: (8) cultivars

Extra Hint: (9) lower

Extra Hint: (10) photosynthesis

Extra Hint: (11) slower

Extra Hint: (12) outcompeted

Extra Hint: (13) mutations

Extra Hint: (14) sunny

Extra Hint: (15) reflects

Extra Hint: (16) transpiration

Extra Hint: (17) adapted

The leaf below is variegated. Define the term 'variegated' A plant with leaves that have two or more different colours

Compare the photosynthetic rate of areas A, B and C in the leaf A = no photosynthesis B = medium photosynthetic rate vs. A and C / higher photosynthetic rate than A, lower than C C = Highest photosynthetic rate

An all-green plant produced a new shoot with these variegated leaves. What do you call the variegated shoot? The new shoot is called a 'sport' (and is what the variegated section will be propagated from)

A variegated plant produces a new shoot that's all green. What do you call this? Reversion. Reverted shoots (all green) are typically cut out of a plant to maintain the variegated aesthetic

What do you call variegated plants that rarely or never produce all-green shoots? Stable.

The photograph shows a waterlily.

Waterlilies must be grown submerged in water. What is the general term for plants that grow in ponds and lakes?
Waterlily leaves are on the water surface and their rhizomes (a type of stem) are submerged, growing at the bottom of the pond/lake. What connects the rhizome to the leaf's lamina?
How are waterlily leaves able to float?
What are the advantages of floating leaves?
What are the disadvantages of floating leaves?
State the benefits of including a naturalistic pond in a garden.

1. Waterlilies must be grown submerged in water. What is the general term for plants that grow in ponds and lakes?

Aquatic plants

2. Waterlily leaves are on the water surface and their rhizomes (a type of stem) are submerged, growing at the bottom of the pond/lake. What connects the rhizome to the leaf's lamina?

The petiole

3. How are waterlily leaves able to float?

Waterlily leaves contain aerenchyma cells, which form a spongy, air-filled tissue. The higher proportion of air in waterlily leaves allows them to float.

4. What are the advantages of floating leaves?

In an aquatic environment leaves that float can access the higher light levels on the water surface. This means they're in a better position for photosynthesis, resulting in greater carbohydrate production. This allows the plant to sustain a potentially faster growth rate, giving it a competitive advantage.

Floating leaves shade the water below, reducing the potential for submerged aquatic plants to outcompete the waterlily.

5. What are the disadvantages of floating leaves?

Floating leaves require the production of aerenchyma, which is energetically expensive for the plant. Floating leaves are also more accessible to various herbivores compared to submerged leaves.

6. State the benefits of including a naturalistic pond in a garden.

Ponds offer habitat to wildlife, including exclusively aquatic wildlife. This increases garden biodiversity. Higher garden biodiversity means the balance of herbivores and natural predators is more likely to be kept in balance, reducing damage to garden plants from herbivores.

Naturalistic ponds with sloping sides offers water to wildlife, which is important when there are prolonged dry spells in summer and water becomes scarce.

Ponds allow aquatic plants to be grown that otherwise wouldn't feature in a garden.

Ponds provide increased interest in a garden and can be utilised to practice mindfulness, benefitting people's wellbeing.

The leaf photographed has produced a small plantlet.

This leaf has totipotent cells. What is totipotency?
In what tissue are totipotent cells found?
What types of organ do leaf cuttings like this produce?
What adaptation does this leaf have that enables it to survive if detached from the parent plant and produce the plantlet pictured?
What benefit does leaf totipotency offer in horticulture?

1. This leaf has totipotent cells. What is totipotency?

Totipotency is the ability of a cell to differentiate into any specialised cell type.

2. In what tissue are totipotent cells found?

Meristem tissue.

3. What types of organ do leaf cuttings like this produce?

Stems, roots, leaves, eventually flowers and fruits (essentially all organs found in the parent plant).

4. What adaptation does this leaf have that enables it to survive if detached from the parent plant and produce the plantlet pictured?

This leaf has succulence, which means it has hydrenchyma tissue that stores water. This enables it to survive a period of detachment from the parent plant until some of the totipotent cells at the point of detachment differentiate into leaves and roots.

5. What benefit does leaf totipotency offer in horticulture?

Leaf totipotency enables horticulturalists to propagate a variety of plants clonally. This allows production of cultivar plants, and preservation of rare species through clonal reproduction. Adult plants (those of flowering age) produced from leaf cuttings are likely to flower sooner than seed grown plants of the same type. Leaf cuttings can by undertaken without highly specialist equipment and highly trained staff, unlike tissue culture. This makes it achievable in most garden settings.

Only woody eudicotyledons undergo secondary thickening
Secondary thickening is exclusive to woody angiosperms
Some monocotyledons undergo secondary thickening
Secondary thickening involves the lignification of xylem and tracheid vessels
Gymnosperms (conifers) contain only tracheid vessels, which undergo secondary thickening
Secondary thickening is integral to enabling plants to retain above ground parts and produce growth new growth from stems high above ground level
Plants have evolved secondary thickening primarily as a way to keep their foliage above seasonal flooding of river flood planes
Bark has evolved in woody plants as a protective layer around the trunk's cambium
The primary reason for thickened bark on plants like cork oak (Quercus suber) is to prevent pests from accessing the cambium beneath

Answers: 1. False - gymnosperms also undergo secondary thickening (Magnoliids also undergo secondary thickening, but knowledge of this is beyond RHS level 2) 2. False - in addition to woody angiosperms, gymnosperms also undergo secondary thickening 3. False 4. True 5. True 6. True 7. False - the primary reason for secondary thickening is to enable plants to compete with each other for light 8. True 9. False. Whilst thickened bark can also help prevent entry of pests, the primary reason for its evolution is to insulate the cambium layer below the bark from heat that occurs during forest fires. Thickened bark is typically resistant to burning.

Decide if the statements below are true or false:

What are the benefits of trees to a garden?

Trees have numerous benefits to a garden, including:

Trees create habitats for wildlife, increasing garden biodiversity
Trees create year-round structure in a garden
Trees can be used to create focal points in a garden
Trees can be used to frame views or frame pathways, which is an important element of garden design
Trees add seasonal interest, particularly deciduous trees whose leaves emerge in spring, remain through summer and often turn bright autumnal colours before revealing bare stems in winter. In some species their bare stems are colourful, adding additional winter interest.
Trees can grow tall enough to screen unsightly views or eyesores
Trees can have deep roots that extract nutrients from deep in the soil. When they shed leaves, some of these nutrients are enter topsoil, benefitting soil nutrition to understory plants

How can shrubs be used to create privacy in a garden?

Shrubs can be pruned/trimmed to fixed dimensions, creating hedges. These can be used to create privacy if used along the garden's boundary by blocking views into the garden.
Shrubs can be maintained as hedges within gardens, compartmentalising areas to create visual privacy.
Shrubs can be allowed to grow into natural forms in e.g. shrubberies or mixed borders. These can also be used to compartmentalise gardens, creating privacy.

How can woody plants be used to maximise biodiversity in a garden?

Biodiversity can be maximised through use of woody plants in the following ways:

Plant a range of different woody plant species. This increases biodiversity through increasing the total number of plant species in the garden. Different wildlife associate with different woody plant species, so increased biodiversity of garden wildlife correlates with increased woody plant diversity.
Plant a range of trees, shrubs, evergreen and deciduous plants. These create different heights and coverage to enable different wildlife species to feed, nest and rest.
Keep deadwood on site, for example by creating log piles. some garden wildlife, like certain beetle larvae, feed on dead wood. Dead branches and twigs can be used to top leaf piles made in autumn, preventing the leaves blowing away. This allows wildlife such as hedgehogs to hibernate within the garden.
Keep woody plants' leaf fall within the garden, ideally using it as a mulch. Detritivores and decomposers feed on dead organic matter so fallen woody plant leaves support their biodiversity.

The photograph shows a Pyracantha coccinea (pyracantha) stem in spring

Name the stem adaptation labelled A.
What is the function of this adaptation?
What botanical part of the plant is adaptation A formed from?
On what part of a stem can adaptation A be found (if present)?
State a disadvantage of producing adaptation A.
Why is adaptation A produced despite the disadvantage?

1. Name the stem adaptation labelled A.

Thorn.

2. What is the function of this adaptation?

Thorns are a defence structure to deter herbivory, typically from larger herbivores such as deer or rabbits.

In some species thorns can also aid climbing or scrambling stems to hold position amongst other vegetation, enabling the plant to position its leaves in higher light/less shaded locations. This optimises potential for photosynthesis. It also allows the plant to position its flowers where they are more visible to pollinators, improving the likelihood of successful pollination.

(Note that thorns are primarily defence structures. In few thorn-producing species do they also aid a climbing habit, unlike other adaptations for climbing. However, in the exam marks will be awarded for including their role in enabling some plants to climb).

3. What botanical part of the plant is adaptation A formed from?

Thorns are modified stems.

4. On what part of a stem can adaptation A be found (if present)?

Thorns are modified axillary shoots, which are found at nodes/nodal areas.

5. State a disadvantage of producing adaptation A.

Thorns are energetically expensive for a plant to produce, meaning less energy is available for growth and reproduction vs. not producing thorns.

6. Why is adaptation A produced despite the disadvantage?

There is a net benefit to producing thorns. The energy used to produce them is offset by not losing as many leaves to herbivory. This gives thorn producing plants a competitive advantage over plants that don't produce protective structures, improving their survival.

The photograph shows a Rosa sp. (rose) stem. The pointed, curved structures are usually called thorns but this is botanically incorrect, they are actually __________. Note that (as stated in the Unit 2 book) the RHS level 2 theory syllabus does not list this particular adaptation, but in this author's opinion it's essential knowledge and therefore has been included in the Unit 2 book.

What is the missing word that fits in the gap (_____________) above?
What is the function of this adaptation?
From what part of the plant's stem is this adaptation derived from?
Other than stems, where else can this adaptation form?

1. What is the missing word that fits in the gap (_____________) above?

Prickles

(singular: prickle)

2. What is the function of this adaptation?

Prickles are a defence against herbivory to prevent loss of foliage and stem damage. They can also aid climbing, particularly when recurved as they hook onto other vegetation. This allows the plant to position its leaves in higher light, increasing the potential rate of photosynthesis. It also allows the plant to position its flowers where they are more visible to pollinators, improving the likelihood of successful pollination.

3. From what part of the plant's stem is this adaptation derived from?

Prickles are outgrowths of the epidermis.

4. Other than stems, where else can this adaptation form?

Prickles can also form on the surfaces of leaf petioles and leaf veins.

The photograph shows a Vitis sp. (grape relative) which has attached itself to a metal railing.

What is the adaptation that allows it to cling to the railing?
What part of the plant forms this adaptation?
Where on a stem does this adaptation arise from?
What is the function of this adaptation?

1. What is the adaptation that allows it to cling to the railing?

A stem tendril.

2. What part of the plant forms this adaptation?

Stem tendrils are modified stems.

3. Where on a stem does this adaptation arise from?

Stem tendrils always arise from nodal areas. They develop from axillary buds.

4. What is the function of this adaptation?

Stem tendrils allow a plant to climb by attaching to nearby vegetation. This allows a climbing plant to grow taller and position its leaves in the optimum position for photosynthesis. It also allows a climbing plant to position its flowers where they are more visible to pollinators, improving the likelihood of successful pollination.

The photograph shows Parthenocissus quinquefolia (Virginia creeper) with an adaptation that allows it to adhere to surfaces.

What is the adaptation that allows it to cling to surfaces?
What part of the plant forms this adaptation?
What issues can this adaptation present if a plant with this adaptation is planted close to a building?

1. What is the adaptation that allows it to cling to surfaces?

These are stem tendrils that branch, with the branches terminating in suction cups that attach to surfaces.

2. What part of the plant forms this adaptation?

These are stem adaptations.

3. What issues can this adaptation present if a plant with this adaptation is planted close to a building?

Stem tendrils with suction cups can adhere to the building's walls; they do not need a support structure unlike other climbers with twining stem tendrils. This means the potential spread of these suction cup climbers is indefinite. The climber can grow where it's unwanted, such as over windows or roofs. Maintenance can become problematic as it may require tall ladders to remove the climber from guttering, roofs and other high up building features. If left unchecked the climber can damage building features such as guttering, or damage roof tiles when removed. The suction cups adhering to painted walls may remove paint if the plant is pulled off surfaces, increasing maintenance further as repainting will be needed.

The photograph shows Ipomea tricolour 'Heavenly Blue' (morning glory 'Heavenly Blue') stems.

What stem adaptation is shown?
State the purpose of this adaptation.
State the benefits of this adaptation.
How can this plant be successfully used as seasonal cover for a closeboard fence? (note: a closeboard fence has horizontal panels with no gaps, presenting a relatively smooth, uniform frontage)

1. What stem adaptation is shown?

Twining stems

2. State the purpose of this adaptation.

Twining stems facilitate climbing

3. State the benefits of this adaptation.

Climbing allows a climbing plant to grow taller and position its leaves in the optimum position for photosynthesis. It also allows a climbing plant to position its flowers where they are more visible to pollinators, improving the likelihood of successful pollination.

4. How can this plant be successfully used as seasonal cover for a closeboard fence? (note: a closeboard fence has horizontal panels with no gaps, presenting a relatively smooth, uniform frontage)

Twining climbers cannot adhere to smooth surfaces, therefore a support structure needs to be installed onto the fence. There should be a gap, e.g. 3 - 5cm, between the support structure and the fence to allow for easier twining action and stem expansion, as well as improved airflow through the plant. The structure could be trellis or high-tension string or wire. Both of these provide narrow supports that the Ipomea stems can twine around, mimicking branches and stems in nature.

The photograph shows Fragaria ananassa (strawberry).

What stem adaptation is shown?
State the purpose of this adaptation.
Explain the benefit of this adaptation.
How is this adaptation used in horticulture?
What are the disadvantages of this adaptation in horticulture?

1. What stem adaptation is shown?

Stolons/runners

2. State the purpose of this adaptation.

Stolons/runners spread out from the parent plant into nearby spaces. They produce roots and new shoots at nodes (in the case of strawberries, a plantlet is produced). This enables colonisation of new areas.

3. Explain the benefits of this adaptation.

Colonisation of new areas means that if the parent plant is damaged or dies the plants derived from that parent survive, facilitating continuation of the species. Colonisation via stolons/runners means the young, developing plants derived from nodal areas on the stolon/runner are supported by the parent plant, improving their chances of survival vs. seeds/seedlings.

4. How is this adaptation used in horticulture?

Plants derived from stolons/runners are clonal, meaning they are genetically identical to the parent plant. If the parent plant has desirable characteristics, such as disease resistance or particularly tasty fruit in strawberry plants, new identical plants can be easily obtained. This makes propagation relatively quick and inexpensive vs. other clonal propagation such as tissue culture. Plants can be propagated on a garden scale without specialist equipment - for example, plantlets can be allowed to develop over summer and then dug up and transplanted in autumn. In the case of strawberries the parent plant is relatively short-lived (for a perennial) so after a few years it can easily be replaced from a stolon-runner derived plantlet.

5. What are the disadvantages of this adaptation in horticulture?

Stoloniferous plants can quickly spread outside of their intended area and become, essentially, a weed in places. This increases the maintenance associated with that plant through the growing season as stolons/runners need to be removed periodically.

The plant pictured dies down in autumn and reemerges from the soil in spring. What type of plant is it? A deciduous herbaceous perennial

Answers: 1. Rhizome 2. Rhizomes are underground (or ground level) stems that spread laterally away from the parent plant. 3. Rhizomes have nodal areas that can produce roots and shoots. This means new stems and roots can grow at a distance from the parent plant, allowing it to colonise new areas. This improves the individual's chance of survival, and by extension survival of the species. 4. Rhizomatous plants can be divided into separate, clonal plants. This allows horticulturalists to increase the number of individuals of a particular plant, including cultivars. This is a quick, cheap and easy form of propagation. 5. Some rhizomatous perennials spread very rapidly and can become weeds, for example Mentha spicata (mint), which is sold as a herb. It also means that most rhizomatous perennials will need periodic lifting and dividing to maintain desired dimensions, which increases the maintenance requirement vs. other growth habits, such as rosette forming plants.

In the photo, letters A, B and C show the order each stem emerged from the soil through the growing season. Stem A emerged first, stem B a month later, and stem C a month after that.

Name the underground adaptation that has produced this sequence of growth.
Define your answer to Q1.
What are the benefits of this adaptation to a plant?
What are the advantages of this adaptation in horticulture?
What are the disadvantages of this adaptation in horticulture?

1. The photograph shows Mentha spicata (mint), which has been grown in a pot for several years. It is lying on its side in this photograph. Using your knowledge of stem adaptations, describe what you can see in the photograph.

2. Using your knowledge of stem adaptations, explain why this mint plant has been grown in a pot for several years.

3. Suggest how this plant could continue to be cultivated in a garden situation.

The photograph shows many upright stems that appear herbaceous, emerging from the growing media. In the upper layer of growing media within the pot there is a dense mat of tightly packed white rhizomes. Beneath this there are vertical roots extending downward.

2. Using your knowledge of stem adaptations, explain why this mint plant has been grown in a pot for several years.

This plant has a vigorous rhizomatous growth. If grown in the open ground these would extend outward from the parent plant, allowing the mint plant to colonise new areas where it may not be wanted - therefore it will become a weed in places. By growing it in a pot the rhizomes can be contained, preventing it becoming a weed.

3. Suggest how this plant could continue to be cultivated in a garden situation.

This plant could:

Be potted into a larger pot, allowing it to become a larger specimen in time.
Be split and divided. A section could be kept and potted; additional divisions could also be potted.

The photograph shows a Solanum tuberosum (potato) plant with a new shoot.

Define the term 'organ of perennation'.
Name the organ of perennation shown in the photograph of Solanum tuberosum.
From what point on the organ of perennation is the new shoot developing?
Explain how this organ of perennation can develop from a seed grown Solanum tuberosum.

1. Define the term 'organ of perennation'.

An organ of perennation is a botanical structure that stores carbohydrate (energy) and water, allowing a plant to survive periods deleterious to growth, such as cold winters or dry seasons. Organs of perennation contain adventitious buds that can develop into new shoots and roots during the growing season.

2. Name the organ of perennation shown in the photograph of Solanum tuberosum.

Stem tuber

3. From what point on the organ of perennation is the new shoot developing?

New shoots develop from nodes on the potato's stem tuber. Sometimes these are referred to as 'eyes' when incipient young shoots can be seen.

4. Explain how this organ of perennation can develop from a seed grown Solanum tuberosum.

A Solanum tuberosum seed germinates at the start of the growing season. In the first growing season it develops a root system and leafy stems above ground. During the first growing season the underground part(s) of the stem send out rhizomes. Sections of the rhizome swell up, storing carbohydrate in the form of starch. These swollen sections of rhizome are stem tubers.

The photograph shows the corms of Crocosmia x crocosmiiflora (montbretia).

What part of the plant is adapted for form a corm?
What are the benefits to a plant of producing corms?
What are the horticultural benefits of corms?

1. What part of the plant is adapted for form a corm?

A corm is a stem adaptation.

2. What are the benefits to a plant of producing corms?

Corms are organs of perennation, allowing a plant to survive periods deleterious to growth through dormancy. They also allow a plant to colonise new areas, improving survival chances for the species.

3. What are the horticultural benefits of corms?

Corms can be used to easily propagate a plant, allowing an individual to be planted in several areas of a garden.
Being dormant, corms can be lifted and packaged for sale, surviving relatively long periods out of the ground. This is useful in horticultural retail.
It's also a relatively low carbon-footprint way to transport plants vs. potted specimens which are heavier.
If soil is washed from them, it also lowers the biosecurity risks of introducing new pests or pathogens to a garden vs. potted plants.

The photograph shows a cactus, which grows in arid regions.

How is the stem of this cactus adapted to survive its arid environment?
How is this cactus adapted to reduce its vulnerability to herbivores?
How can the cactus take advantage of sunlight without leaves?

1. How is the stem of this cactus adapted to survive its arid environment?

The cactus has a succulent stem which stores water. When it does rain the roots absorb water, which is stored in the succulent stem.
The cactus has a thick waxy cuticle to reduce water loss.
The cactus has a relatively low density of stomata, reducing water loss.
The stomata only open at night when it's cooler, so less water vapour is lost via transpiration than if they opened during the day.
The stem has a relatively low surface area:volume ratio. This means it has a relatively low surface area through which to lose water.

2. How is this cactus adapted to reduce its vulnerability to herbivores?

The cactus has spines. These are sharp and pointed, deterring larger herbivores such as desert rabbits.

3. How can the cactus take advantage of sunlight without leaves?

The cactus has chlorophyll in its stem which can photosynthesise.

Plants only colonise new areas via stem adaptations such as rhizomes.
Rhizomes are a disadvantage in garden plants.
All invasive weeds spread via underground stems.
Stem tubers are an organ of perennation.
Corms are condensed stems that store carbohydrate and do not photosynthesise.
Stolons and runners are botanically different.

Answers: 1. False. Plants can also colonise via seed, stolons/runners, corms, layering and other means. 2. False. Rhizomes can be useful as they allow a plant to grow bigger and make more of a statement in the garden. It also allows them to be divided, a form of clonal propagation. 3. False. Invasive weeds can also spread via seed or stolons/runners. 4. True. 5. True. 6. False. They are essentially the same. The term stolon is typically given to an arching overground stem, where runners lie flat on the ground.

True or false:

The photograph shows the branch of a pine tree. Pine trees can secrete resin.

Name the part of a pine tree stem from which resin is secreted.
What is the benefit to the pine tree of secreting resin?
Some other plants have stems that secrete different substances, such as oil. What is the advantage of this?
Secreting resin or oils has disadvantages. What are they?

1. Name the part of a pine tree stem from which resin is secreted.

Ducts

2. What is the benefit to the pine tree of secreting resin?

Resin is pungent and can deter foraging herbivores such as insects. It's also sticky and can trap pathogens, potentially reducing the incidence of disease in the plant.

3. Some other plants have stems that secrete different substances, such as pungent oil. What is the advantage of this?

Pungent oil can deter herbivory.

4. Secreting resin or oils has disadvantages. What are they?

The production of these substances is energetically expensive for the plant. This reduces the energy available for growth, reproduction and energy storage, which can be a disadvantage to a plant.

The photograph shows the base of a stem cutting which has been kept in water for two months.

What one word encompasses the ability of meristem cells in the stem to differentiate into root cells.
What are the benefits of propagating plants via stem cuttings in horticulture?

1. What one word encompasses the ability of meristem cells in the stem to differentiate into root cells.

Totipotent

2. What are the benefits of propagating plants via stem cuttings in horticulture?

Stem cuttings are a way to clone plants, meaning horticulturalists can propagate specific cultivars of plants.
Most stem cuttings can be undertaken in a garden with relatively low skill and without highly specialist equipment, unlike tissue culture.
Propagating from stem cuttings from adult plants (those at flowering/fruiting age) means the cuttings will flower sooner than if plants were seed grown.
Propagating via stem cuttings eliminates the risk of spreading pathogens or pests associated with the plant's roots, unlike e.g. dividing a rhizomatous herbaceous perennial.

Each number relates to a specific word, so if you think (1)________ is 'bananas' then if (1)________ appears later on in the passage, 'bananas' is the missing word.

How can plant stems be used to create interest in a garden?

Some plants stems can be used for winter display, such as (1) ________ stems. These are a benefit in winter because (2) ________ plants lose their leaves, reducing the range of interest in a garden. Plants with (1) ________ stems brighten a garden. If sited carefully, such as white-barked Betula utilis subsp. jacquemontii planted in a lawn, they can create a (3) ________ point that becomes a greater feature in winter.

Plants with (4) ________ thickening, especially those with evergreen leaves or marcescence, can be used to (5) com________ a garden into different rooms. These plants are tightly clipped to create (6) ________, the height and width of which tends to be uniform. Tall (6) ________ create visual privacy and allow different garden 'rooms' to be (7) ________, such as a 'white garden' room, (5) com________ a vegetable growing area or screening waste bins.

Garden (6) ________ and other woody plant features create habitat for garden (8) ________ such as birds and insects. Birds create (9) ________ high in woody plants, enabling them to more safely rear young. Therefore woody plants, which have (4) ________ thickening as a stem adaptation, can increase garden (10) b________.

Pruned stems of woody plants, such as hazel coppice, can be used as plant (11) ________, e.g. to create a structure for sweet peas or runner beans to climb up. Runner beans, like wisteria and morning glory vines, have (12) ________ stems that wrap around supports as they grow, another stem adaptation.

Hint: the missing words in a random order supports, focal, wildlife, themed, twining, hedges, coloured, secondary, compartmentalise, biodiversity, nests, deciduous

Extra Hint: (1) coloured

Extra Hint: (2) deciduous

Extra Hint: (3) focal

Extra Hint: (4) secondary

Extra Hint: (5) compartmentalise

Extra Hint: (6) hedges

Extra Hint: (7) themed

Extra Hint: (8) wildlife

Extra Hint: (9) nests

Extra Hint: (10) biodiversity

Extra Hint: (11) supports

Extra Hint: (12) twining

How can plant stems be used to create interest in a garden?

Some plants stems can be used for winter display, such as (1) coloured stems. These are a benefit in winter because (2) deciduous plants lose their leaves, reducing the range of interest in a garden. Plants with (1) coloured stems brighten a garden. If sited carefully, such as white-barked Betula utilis subsp. jacquemontii planted in a lawn, they can create a (3) focal point that becomes a greater feature in winter.

Plants with (4) secondary thickening, especially those with evergreen leaves or marcescence, can be used to (5) compartmentalise a garden into different rooms. These plants are tightly clipped to create (6) hedges, the height and width of which tends to be uniform. Tall (6) hedges create visual privacy and allow different garden 'rooms' to be (7) themed, such as a 'white garden' room, (5) compartmentalise a vegetable growing area or screening waste bins.

Garden (6) hedges and other woody plant features create habitat for garden (8) wildlife such as birds and insects. Birds create (9) nests high in woody plants, enabling them to more safely rear young. Therefore woody plants, which have (4) secondary thickening as a stem adaptation, can increase garden (10) biodiversity.

Pruned stems of woody plants, such as hazel coppice, can be used as plant (11) supports, e.g. to create a structure for sweet peas or runner beans to climb up. Runner beans, like wisteria and morning glory vines, have (12) twining stems that wrap around supports as they grow, another stem adaptation.

Decide which of the statements below describes:

fibrous roots, tap roots, or is a false statement.

Only found in eudicotyledonous plants
Only found in monocotyledonous plants
Derived from the radicle
Thicken as they age
Always undergo secondary thickening
Sometimes undergo secondary thickening
Never undergoes secondary thickening
Has a fixed diameter at maturity in each species of plant
Forms a denser root network around the plant than the other root system
In urban areas they can push up paving stones some distance from the base of the plant they've grown from

Answers: 1. False - eudicotyledons have tap roots but gymnosperms also have tap roots. Therefore tap roots are found in more than just eudicotyledonous plants. 2. Fibrous roots. 3. Tap roots. 4. Tap roots. 5. False - only woody plants' tap roots undergo secondary thickening, herbaceous eudicot roots do not produce secondary thickening. 6. Tap roots (woody eudicots and gymnosperm roots have secondary thickening but herbaceous eudicot roots do not have secondary thickening). 7. Fibrous roots. 8. Fibrous roots. 9. Fibrous roots. 10. Tap roots (woody tap roots)

Foraging roots:

The diagram shows a representation of a plant root system.

What type of root system does this represent?
Justify your answer to Q1
Which letter (A, B or C) is the most likely location for active foraging by roots?
Justify your answer to Q3
What is root foraging?
During a calendar year, when is root foraging likely to be most active?
Justify your answer to Q5

1. What type of root system does this represent?

Tap root system

2. Justify your answer to Q1

There is a single, larger primary root arising from the base of the plant stem that has lateral roots branching from it. This is unlike fibrous root systems where many roots of equal diameter arise from the base of the plant.

3. Which letter (A, B or C) is the most likely location for active foraging by roots?

4. Justify your answer to Q3

Areas near the root tips have root hairs, which undertake foraging.

5. What is root foraging?

Root foraging is where actively growing roots, which produce an abundance of root hairs in the zone of differentiation, absorb water and minerals from the soil. The actively growing root grows in a directional way, seeking areas with moisture, oxygen and nutrients.

6. During a calendar year, when is root foraging likely to be most active?

When a plant is producing active root growth, which for most plants is spring, summer and autumn. However, in some winter growing species such as Galanthus nivalis (snowdrop) root foraging happens in winter.

7. Justify your answer to Q5

When plants are in active growth they need water to ensure cell turgor of existing and new cells. Minerals are needed for the manufacture of new organic compounds in a growing plant; minerals are transported from the roots to above ground areas as dissolved ions in the transpiration stream - therefore water is also needed to supply the transpiration stream. In addition, foraging roots grow longer and provide better anchorage to the plant as its above ground parts grow larger and become more exposed to wind-rock.

Root Tropisms:

The photo shows a Geranium cv. rhizome that's been lifted. The rhizome was previously growing horizontally along the soil surface.

Describe the appearance of the roots shown in this photo.
State the direction of root growth before the rhizome was lifted.
Use your knowledge of root tropisms to explain the direction of root growth.
The photo below shows a plant that's been rooted in water on a bright windowsill. Explain the direction of root growth.

1. Describe the appearance of the roots shown in this photo.

The roots are white and grow from the underside of the rhizome, likely from a nodal area.

2. State the direction of root growth before the rhizome was lifted.

They have a downward growth direction.

3. Use your knowledge of root tropisms to explain the direction of root growth.

Roots are positively gravitropic, meaning they grow downward in the direction of gravity, as shown in the photo. Roots are also negatively phototropic, meaning they grow away from light. In the photo the roots have grown downward into the soil, away from daylight coming from above.

4. The photo below shows a plant that's been rooted in water on a bright windowsill. Explain the direction of root growth.

The roots have not been able to respond in a phototropic way because they have been exposed to light on all sides. However, they demonstrate positive gravitropism in their downward growth direction.

The photo shows a Rhus typhina 'Dissecta' with several stems emerging from below soil level. Each year more stems grow from below soil level.

Originally a single-stemmed plant was planted. This plant does not produce rhizomes, stolons/runners, and does not have leaf totipotency that enable leaf cuttings to root.

Explain how this plant produces new stems from below soil level and why this occurs.

This plant has totipotent roots that can produce new stems from the underground root system - adventitious root buds. The stems are negatively phototropic and therefore grow upwards, away from gravity, emerging above ground. Stems arising from adventitious root buds are called suckers.

As the root system extends, new shoots arise further away from the original stem, allowing the plant to colonise new areas. This gives the plant a competitive advantage. If one stem is damaged or attacked by a pest or pathogen, there are other stems that increase the likelihood of this plant's survival.

All plants can produce adventitious root buds.
Adventitious root buds means certain plants can be propagated from their roots.
Root suckers are genetically different from the plant they arise from.
Sometimes root suckers are considered weeds.
It's best practice to cut unwanted root suckers off where they emerge from the soil.

Answers: 1. False. Not all plants produce adventitious root buds. 2. True 3. False. They are genetically identical. 4. True. 5. False. The section of stem left below soil will send up new shoots. It's best to wait until the sucker is pencil thickness (on woody plants) and then pull it up, breaking it from the roots. Waiting until the sucker is pencil thickness means it's strengthened and won't snap as you pull it off the root. Leave it too long and it can be challenging to pull it from the roots.

True or false:

A is not a stem tuber but B is. Both form underground. What is A? A is a root tuber

What are the new shoots on structure A derived from? Adventitious root buds

State the similarities and differences between A and B - A is a root tuber which forms from a swollen section of root, whereas B is a stem tuber that forms from a swollen section of rhizome. - Both are organs of perennation. - Both store starch (energy) - Both can produce new shoots, from which new roots arise.

The photo shows a tomato (Solanum lycopersicum) stem.

What are the white structures emerging from the stem?
Suggest why they are only emerging on one side of the stem.
What is the advantage to the plant of producing these structures?
How can horticulturalists take advantage of this?

1. What are the white structures emerging from the stem?

Adventitious roots

2. Suggest why they are only emerging on one side of the stem.

It's likely that they are emerging from the north-facing side/side that doesn't receive direct light. It could also be that the side producing roots has been resting against a damp surface.

3. What is the advantage to the plant of producing these structures?

Adventitious roots increase the potential for a plant to absorb water and minerals, facilitating its growth. If they grow into the soil they can improve anchorage of a plant and allow it to colonise new areas. Sometimes they are aerial adventitious roots and adhere to surfaces as a climbing aid.

4. How can horticulturalists take advantage of this?

Plants that can produce adventitious roots from their stems can be propagated via cuttings or layering. This allows for clonal propagation of plants. Plants that are at the adult stage of their lifecycle and propagated via cuttings will flower sooner than plants grown from seed.

The photo shows an ivy (Hedera helix) stem. There are two types of root emerging from its stem, one circled in white and one in red.

What are the two types of root emerging from the stem?
Which type is circled in white?
Which type is circled in red?
Explain the advantage of the roots circled in red.
How does this adaptation affect how horticulturalists maintain Hedera helix?

1. What are the two types of root emerging from the stem?

Adventitious foraging roots and adventitious climbing roots.

2. Which type is circled in white?

Adventitious foraging roots.

3. Which type is circled in red?

Adventitious climbing roots.

4. Explain the advantage of the roots circled in red.

Adventitious climbing roots adhere to surfaces, allowing the plant to climb upwards, such as up trees, walls or fences. This enables the plant to access higher light levels, improving its potential for photosynthesis. This means more carbohydrate is produced, which supplies more energy for growth and reproduction.

5. How does this adaptation affect how horticulturalists maintain Hedera helix?

As Hedera helix can adhere to surfaces its upward spread is indefinite. This means it can grow outside of desired dimensions, such as growing too high on house walls and even over roofs. Unlike climbers with twining stems, stem tendrils or leaf tendrils, those with adventitious climbing roots care not limited to support structures installed by horticulturalists. Therefore it needs regular pruning through the growing season to prevent it growing too large.

A. Zea mays (sweetcorn)

B. Lupinus cv. (lupin, a legume)

C. Taxodium distichum (swamp cypress)

Match each statement below to one of the plants: A, B or C, above:

An adaptation to low-oxygen soil conditions
Improve stability of the plant
Involve secondary thickening
An adaptation to soils low in nutrients
Contain aerenchyma tissue
Emerge from above ground level
Arise from below ground level
Involve symbiosis with bacteria

Answers: 1 - C 2 - A 3 - C 4 - B 5 - C 6 = A 7 - C 8 - 8

The photo shows a Californian lilac (Ceanothus cv.) in flower. There were several different species of bee visiting the flowers.

Using only what you can see in the photo, describe how the plant's flowers attract bees.
Suggest additional ways that flowers can attract bees (beyond what's shown in the photo).
Define pollination (unit 1 recap).
Suggest a season during which this plant is in flower.
There is an identical Ceanothus cultivar nearby, but no other Ceanothus plants for miles around. How does this impact pollination?

1. Describe how the plant's flowers attract bees.

The flowers are visible above the foliage of the plant, making them more obvious from a distance.
The flowers are brightly coloured, which also makes them stand out from a distance.
The flowers appear to all be open at the same time, creating a bigger visual impact to attract pollinators.

2. Suggest additional ways that flowers can attract bees (beyond what's shown in the photo).

The flowers could be scented to attract bees.
The flowers could contain nectaries that produce nectar, attracting repeated visitation by bees.

3. Define pollination (unit 1 recap).

Pollination is the transfer of pollen from the stamen of a flower to the stigma of a flower.

4. Suggest a season during which this plant is in flower.

Spring or summer

(These are the seasons when different species of bees are most active and when flowering is most prolific. Very few plants flower in the autumn as it leaves little time for seed development before winter. It's unlikely to be winter if several different species of bee are visiting the flowers - in winter it's predominantly only bumblebees that may flw on mild days).

5. There is an identical Ceanothus cultivar nearby, but no other Ceanothus plants for miles around. How does this impact pollination?

Cross-pollination is highly unlikely as few bees will happen to transfer pollen from plants located many miles away. If the two plants in this locality are identical cultivars, this means they are genetically identical. Therefore any pollination that occurs within or between these plants is self-pollination.

The photo shows a pine tree (Pinus sp.)

What mode of pollination does this plant have?
Justify your answer to Q1.
Suggest how this plant maximises its potential for pollination.
What major group of monocotyledonous plants shares this mode of pollination?
How does the group of plants named in Q4 maximise their potential for pollination?

1. What mode of pollination does this plant have?

Wind pollination

2. Justify your answer to Q1.

Pine trees are gymnosperms (conifers) and all gymnosperms are wind pollinated. In addition, the reproductive structure (male or female cone) shown is dull in colour, suggesting wind pollination).

3. Suggest how this plant maximises its potential for pollination.

It's likely that the cones are produced high on the tree to maximise their exposure to wind. Male cones produce copious, small, lightweight pollen that can travel far on the wind, increasing likelihood of reaching female cones of a different plant of the same species, resulting in cross-pollination. It's likely that male and female cones on a species are active during a similar time period, meaning when pollen is released by male cones, female cones are able to receive the pollen, resulting in pollination.

4. What major group of monocotyledonous plants shares this mode of pollination?

Grasses (Poaceae would also be accepted - grasses are part of this plant family)

5. How does the group of plants named in Q4 maximise their potential for pollination?

Most grasses produce flowers atop stems above their foliage, maximising their exposure to wind.
Stamens produce copious, small, lightweight pollen that can travel far on the wind, increasing likelihood of reaching stigma's of a different plant of the same species, resulting in cross-pollination.
Flowering of each species occurs in the same time period, increasing the likelihood of cross-pollination.

Flowers tend to be small and held close to the plant.
When herbaceous plants produce flowers closer to ground level than flowers produced on herbaceous plants in other seasons.
When most wind pollinated deciduous trees flower.
When most garden plants used in herbaceous borders flower.
When plants from dry summer climates are likely to flower.
Insect pollinated flowers are often powerfully fragrant, but small.
When there is higher competition for pollinators compared to other seasons.
When there is a low abundance of active pollinating insects.
Butterfly pollinators are most active in this season.
When insect pollinators are most likely to be inhibited by the weather.

Answers: (anything in brackets is extra detail/FYI. The one-word season will get the mark) 1. Winter 2. Winter and spring (particularly early spring) 3. Winter or (early) spring 4. Summer or (mid - late) spring 5. Autumn, winter or spring 6. Winter or (early) spring 7. Summer 8. Winter 9. Summer 10. Winter

Match each statement to ONE season. Some statements match more than one season - you only need to name one season correctly. If you write more than one season for a statement, only mark the first season you wrote down.

The seasons are: spring, summer, autumn, winter.

This photo was taken during the month of October in the UK. The plant is Cyclamen hederifolium. It was dormant through summer.

This species is not native to the UK. Suggest a climate from which this plant could originate.
With reference to your previous answer, why might this plant flower in the autumn?
State the horticultural merits of growing this plant in a UK garden setting.

Answers: 1. A dry summer climate where rainfall is predominantly in the autumn/winter/spring, e.g. a Mediterranean climate. 2. In its native region it flowers with the onset of autumn rain to support its growth. During autumn it's warmer than winter, so pollinators are more active. It also gives the plant maximum time to develop its seeds before summer dormancy. 3. Few plants flower in autumn in the UK so this plant provides colour and ground-level interest. It provides pollinators with a food source when little else is in flower, supporting garden biodiversity.

Each number relates to a specific word, so if you think (1)________ is 'bananas' then if (1)________ appears later on in the passage, 'bananas' is the missing word.

Wind pollinated flowers and insect pollinated flowers:

Wind pollinated flowers typically have (1) ________ coloured petals or tepals which are (2) ________ in size compared to most insect pollinated flowers. The benefit of this is that wind pollinated plants do not expend much (3) ________ on petal/tepal production compared to insect pollinated flowers. Wind pollinated flowers do not produce (4) s________ because they do not need to attract pollinators.

In contrast, insect pollinated flowers typically have (5) ________ coloured petals that can be (6) ________ enough to acts as a (7) l________ pad for insects. In addition, petals may have markings that are visible to insects that are able to see (8) ________ light (which human's can't see). Some insect pollinated flowers produce (4) s________ to attract pollinators.

Wind pollinated flowers and insect pollinated flowers:

Wind pollinated flowers typically have (1) dull coloured petals or tepals which are (2) reduced/small in size compared to most insect pollinated flowers. The benefit of this is that wind pollinated plants do not expend much (3) energy on petal/tepal production compared to insect pollinated flowers. Wind pollinated flowers do not produce (4) scent because they do not need to attract pollinators.

In contrast, insect pollinated flowers typically have (5) brightly coloured petals that can be (6) large/big enough to acts as a (7) landing pad for insects. In addition, petals may have markings that are visible to insects that are able to see (8) UV (ultraviolet) light (which human's can't see). Some insect pollinated flowers produce (4) scent to attract pollinators.

Hint: the missing words in a random order Large/big, scent, UV / ultraviolet, landing, reduced/small, dull, energy, brightly

Extra Hint: (1) dull

Extra Hint: (2) reduced/small

Extra Hint: (3) energy

Extra Hint: (4) scent

Extra Hint: (5) brightly

Extra Hint: (6) large/big

Extra Hint: (7) landing

Extra Hint: (8) UV / ultraviolet

What is nectar? Nectar is a sugary liquid.

Why do plants produce nectar? Nectar is a high-energy food source for insects. Pollinator insects visit flowers that provide them with nectar. During these visits they pollinate flowers. This means ovules can be fertilised and seeds can be produced, enabling sexual reproduction of plants.

Where is nectar produced? Nectar is produced in the nectaries of flowers.

What is the disadvantage to a plant of producing nectar? Nectar requires a high energy expenditure to produce. This means plants that produce nectar have less energy for other processes like growth.

Only cross-pollination can occur.
Have male and female flowers on the same plant.
One plant can self-pollinate.
One flower can self-pollinate.
Have separate male and female plants.
About half the flowers on a plant can produce seeds.
About half the plants in a population can produce seeds.
Can produce nectar.
This major group of seed-bearing plants is (almost) never hermaphrodite.
Each flower contains male and female parts.
Has flowers that only produce pollen.
Has plants that only produce pollen.

Answers: 1. Dioecious (it's not possible for a plant to pollinate itself - genetically different male and female plants of the same species are required to achieve pollination) 2. Monoecious 3. Monoecious and hermaphrodite 4. Hermaphrodite 5. Dioecious 6. Monoecious 7. Dioecious 8. Hermaphrodite, monoecious, dioecious (all) 9. Gymnosperms (conifers) 10. Hermaphrodite 11. Monoecious, dioecious 12. Dioecious

Match each statement to the type of flower: hermaphrodite, monoecious, dioecious.

Some statements match more than one type of flower.

What type of flowering plant cannot self-pollinate?
In terms of pollination, what is self-incompatibility?
What term describes the stigma ripening before the anthers in order to reduce the chance of self-pollination?
What term describes the anthers ripening before the stigma in order to reduce the chance of self-pollination?
Why do monoecious plants generally have a lower likelihood of self-pollination than hermaphrodite flowers?

1. What type of flowering plant cannot self-pollinate?

Dioecious

2. In terms of pollination, what is self-incompatibility?

When a plant will not allow its own pollen to develop on its stigma.

3. What term describes the stigma ripening before the anthers in order to reduce the chance of self-pollination?

Protogyny

4. What term describes the anthers ripening before the stigma in order to reduce the chance of self-pollination?

Protandry

5. Why do monoecious plants generally have a lower likelihood of self-pollination than hermaphrodite flowers?

The male and female flowers are separate, meaning it's more likely that pollen from a genetically different plant of the same species will pollinate the stigma than in hermaphrodite flowers, where stigma and anthers are in close proximity.

Each number relates to a specific word, so if you think (1)________ is 'bananas' then if (1)________ appears later on in the passage, 'bananas' is the missing word.

Seeds contain an (1) ________, which can develops when a seed (2) g________. At this point the (1) ________ sends down a (3) ________, and upward growing (4) ________. The (3) ________ doesn't persist in monocotyledons, but in (5) ________ it becomes the primary root of the (6) ________ root system. Until the (4) ________ develops leaves and begins to (7) ________ the seedling cannot gain energy from light to power its growth. The seed contains an energy store that's rich in (8) c________ and (9) f________/o________. In (5) ________ it's stored in the seed's (10) ________ (seed leaves), whereas in monocotyledons energy is stored in a structure called the (11) ________.

Surrounding the seed is a protective coat called the (12) ________. There is a tiny hole in the (12) ________ called the (13) ________, which allows water to enter the seed.

A seed will not (2) g________ unless conditions are suitable. The main external conditions that affect (2) g________ include (14) t________, (15) m________ and in some species, (16) l________.

Seeds contain an (1) embryo, which can develops when a seed (2) germinates. At this point the (1) embryo sends down a (3) radicle, and upward growing (4) plumule. The (3) radicle doesn't persist in monocotyledons, but in (5) eudicotyledons it becomes the primary root of the (6) tap root system. Until the (4) plumule develops leaves and begins to (7) photosynthesise the seedling cannot gain energy from light to power its growth. The seed contains an energy store that's rich in (8) carbohydrate and (9) fats/oils. In (5) eudicotyledons it's stored in the seed's (10) cotyledons (seed leaves), whereas in monocotyledons energy is stored in a structure called the (11) endosperm.

Surrounding the seed is a protective coat called the (12) testa. There is a tiny hole in the (12) testa called the (13) micropyle, which allows water to enter the seed.

A seed will not (2) germinate unless conditions are suitable. The main external conditions that affect (2) germination include (14) temperature, (15) moisture and in some species, (16) light.

Hint: the missing words in a random order plumule, endosperm, testa, embryo, radicle, light, micropyle, eudicotyledons, temperature, photosynthesise, fats/oils, moisture, cotyledons, germinates or germination, tap, carbohydrates,

Extra Hint: (1) embryo

Extra Hint: (2) germinates

Extra Hint: (3) radicle

Extra Hint: (4) plumule

Extra Hint: (5) eudicotyledons

Extra Hint: (6) tap

Extra Hint: (7) photosynthesis

Extra Hint: (8) carbohydrate

Extra Hint: (9) fats/oils

Extra Hint: (10) cotyledons

Extra Hint: (11) endosperm

Extra Hint: (12) testa

Extra Hint: (13) micropyle

Extra Hint: (14) temperature

Extra Hint: (15) moisture

Extra Hint: (16) light

Seeds have a larger energy store
Seeds are more likely to be wind dispersed
Seeds are more likely to be dispersed by animals
Seeds are less likely to require light to germinate
Seeds generally do not store for a long time
Produces a smaller seedling
Are more attractive to larger herbivores
Often have a thick, protective testa
Each seed is a smaller investment by the parent plant.
Of the total seeds produced each year, a lower percentage are likely to survive and reach adulthood.

Answers: 1. B 2. A 3. B 4. B 5. B 6. A 7. B 8. B 9. A 10. A

The images show seeds of different sizes. Decide whether the statements below relate to the following:

A. a larger number of smaller seeds

B. a smaller number of larger seeds

Each numbered statement below will match either A or B. Statements are comparative between A and B.

Suggest a mode of seed dispersal for each of the images A - I.

(Some have the same mode of dispersal)

Give a reason to justify each of your suggestions.

Answers: A. Frugivory - colourful, fleshy fruit attract herbivores to eat them B. Wind - these have wings (samara's) that catch the wind C. Wind - these have feathery attachments that catch the wind D. Explosive - as the pod dries tension builds, eventually exploding open to scatter the seeds (this is typical of seed pods of the legume family) E. Attachment - these small, dull coloured seeds are covered in hooked hairs that attach to fur or feathers of passing animals. F. Water - many aquatic plants have buoyant seeds. G. Wind - these seeds have a parachute like attachment that catches the wind. H. Frugivory - colourful, fleshy fruit attract herbivores to eat them. I. Hoarding - acorns are large seeds that are collected and (if not immediately eaten) are buried and sometimes forgotten.

Decide if each of the statements below matches to either:

Physical dormancy
Physiological dormancy
Morphological dormancy

Each statement matches one type of dormancy.

Dormancy is imposed by chemicals in or around the seed.
At the point of dispersal the embryo is immature.
Washing of the seed via rainfall can remove germination inhibitors.
Typically features a hard seed coat that's impermeable to water.
Stratification can overcome this dormancy mechanism.
The protective seed coat can be broken down by exposure to stomach acid (when passing through a herbivore's digestive tract), enabling later germination.
The germination is not hormonally stimulated until after a period of cold, damp conditions.
Scarification can overcome this dormancy mechanism.
After-ripening of seeds results in staggered germination.

Answers: 1. Physiological 2. Morphological 3. Physiological 4. Physical 5. Physiological 6. Physical 7. Physiological 8. Physical 9. Morphological

What is the difference between orthodox seed and recalcitrant seed?
What are the differences in storage of orthodox and recalcitrant seed?

1. What is the difference between orthodox seed and recalcitrant seed?

Orthodox seed has a low moisture content, typically under 10%. Recalcitrant seed have a higher moisture content and cannot survive drying.

Orthodox seed can survive long periods if its metabolic rate remains low. Recalcitrant seeds tend to have a higher metabolic rate so their energy store is depleted at a faster rate.

2. What are the differences in storage of orthodox and recalcitrant seed?

Orthodox seed can be successfully stored for long periods if kept dry and at a low temperature, for example in a fridge.

Recalcitrant seed cannot be stored for long periods as their viability drops due to their higher metabolic rate.

State the environmental conditions can stimulate germination a non-dormant seed of a temperate (non-tropical) species.

Define the term quiescence.

3. State the advantages of quiescent seeds in horticulture.

Quiescent seeds pose less challenge to germinate because a dormancy mechanism does not need to be overcome. Therefore, for example, they can be sown in spring and will germinate if exposed to moisture, a suitable temperature (e.g. 15c - 18c), and for some species - light.

Many edible annual and biennial crops have been selected for quiescent seed that germinates readily and uniformly after sowing, resulting in a more predictable harvesting timeframe.

Quiescent seeds that are sown as a propagation means within gardens, or for eventual sale as plants, can be produced with greater ease than dormant seeds. For example, needing to scarify or stratify seeds takes more time, skill and resources than sowing quiescent seed.

2. Name the environmental factors that can trigger a quiescent seed to germinate.

4. State the disadvantages of quiescent seeds.

5. How should quiescent seeds be stored to maximise the length of their viability? Give a reason for your answer.

Quiescent seed should be stored in a fridge to keep its temperature low, reducing the rate of respiration in the seed. This means its energy store is not used up as quickly, improving the duration of its viability.

Quiescent seed should also be stored dry to reduce the risk of pathogens infecting the seed.

Hint: the missing words in a random order Large/big, scent, UV / ultraviolet, landing, reduced/small, dull, energy, brightly

Extra Hint: (1) dull

Extra Hint: (2) reduced/small

Extra Hint: (3) energy

Extra Hint: (4) scent

Extra Hint: (5) brightly

Extra Hint: (6) large/big

Extra Hint: (7) landing

Extra Hint: (8) UV / ultraviolet

What is secondary thickening?
What is the benefit of secondary thickening to plants?
What are the disadvantages of secondary thickening?

1. What is secondary thickening?

Secondary thickening is the lignification of xylem (or tracheids in conifers) which strengthens stems and is part of enabling stems to persist perennially above ground. Woody plants (trees and shrubs) undergo secondary thickening.

2. What is the benefit of secondary thickening to plants?

Secondary thickening strengthens stems, allowing them to grow taller to better compete for light with a lower risk of damage due to high winds or heavy rain compared to herbaceous stems.

Secondary thickening is part of enabling stems to be perennial and grow taller each year, again improving a plant's ability to compete for light.

3. What are the disadvantages of secondary thickening?

Lignification is a high energy investment, resulting in a slower growth rate than herbaceous plants can potentially attain. This can be a disadvantage especially when woody plants are young, such as seedlings - they may struggle to compete with nearby herbaceous plant competition.

Woody plants have many different uses in gardens. Match each statement (1 - 10) to the garden use (A - F).

Each statement matches one main use, but secondary uses can be given in brackets.

Uses:

A. Height and structure

B. Privacy

C. Compartmentalising gardens

D. Screening

E. Shelterbelts

F. Habitat for wildlife

A shrub is selected for its spring flowers that attract pollinators and autumn berries that attract birds, e.g. Sambucus nigra (elder).
A 1.8m high evergreen hedge around the garden periphery.
A 2.5m high hedge of Fagus sylvatica (beech), a marcescent species, planted to the south west of an exposed garden.
Internal hedges used to create different garden 'rooms'.
Repeated spheres of a small leaved evergreen shrub such as Ilex crenata (Japanese holly).
A mixed species hedge with largely native woody plants.
A 1.5m tall Ligustrum vulgare (wild privet) hedge around the area where bins are stored.
An evergreen tree such as Magnolia grandiflora 'Kay Parris' (southern magnolia 'Kay Parris' planted to block views of an unsightly feature outside the garden.
A focal point tree planted in a lawn.
Taxus baccata (yew) planted as a tightly clipped hedge separating one garden area from another.

Answers: 1 - F 2 - B (D, E, F) 3 - E (F) 4 - C (A, B, D, F) 5 - A (structure) (F) 6 - F (A, B, D) 7 - D (A, C, F) 8 - D (A, B, F) 9 - A (F) 10 - C (A, B, D, F)

Define the term 'herbaceous perennial'
Name the organs of perennation that that herbaceous perennials can potentially have.
What are the advantages and disadvantages to deciduous herbaceous perennials of being deciduous?
What are the advantages and disadvantages to evergreen herbaceous perennials of being evergreen?

1. Define the term 'herbaceous perennial'

A non-woody plant that lives for more than two years.

2. Name the organs of perennation that that herbaceous perennials can potentially have.

Rhizome, stem tuber, swollen tap root, root tuber, bulb, corm.

3. What are the advantages to deciduous herbaceous perennials of being deciduous?

Loosing their above ground parts means they do not need these parts to withstand winter cold; they can survive adverse winter weather via an organ of perennation below ground where temperature is buffered. This means they put less energy into each leaf and above ground stem produced, meaning they can have a faster growth rate than evergreens.
In addition to the point above, this means they can grow taller during the growing season, better competing for light and holding their flowers higher, improving potential for pollination.
There is no risk of damage to living above ground parts in winter, which could result in entry points for pathogens.

4. What are the advantages to evergreen herbaceous perennials of being evergreen?

Their evergreen leaves can photosynthesise during mild winter weather, replenishing their starch store. This allows them to overwinter more successfully.
Their leaves shade the soil all year round, blocking light from reaching the soil. This both reduces weed germination, reducing potential competition, and shades the soil in summer which reduces evaporative moisture loss from the soil surface.

Name the habitats that plants with a low growth habit often come from.
How are low growing plants adapted to each of the habitats named in Q1?
Describe garden situations that would best replicate each of the habitat types named in Q1.

1. Name the habitats that plants with a low growth habit often come from.

Alpine, mediterranean, woodland understory.

2. How are low growing plants adapted to each of the habitats named in Q1?

Alpine:

Low, tufted habit with generally low flowering height to reduce the risk of physical damage from the wind, and reduce wind chill.
Leaves and stems that are adapted to minimise water loss in thin, dry montane soil. This may include hirsute leaves/stems, succulence, thick waxy cuticle, grey-green/pale colouring to reduce leaf heating and therefore rate of transpiration.
Many are evergreen, meaning in their habitat's short growing season plants don't need to spend time and energy developing new leaves each season. This means they can take advantage of clement weather immediately, photosynthesising when temperature and light levels allow.
Flowering is a mass event in spring, giving time for seeds to develop in the short growing season.

Mediterranean:

Plants have adaptations to reduce water loss via transpiration during summer, such as hirsute leaves/stems, succulence, thick waxy cuticle, grey-green/pale colouring.
Plants can reduce growth and go dormant/semi-dormant in summer if the soil becomes dry, reducing need for water to support new growth.
Some mediterranean climate woody plants have thick bark to resist heating during forest fires, protecting the cambium beneath.

Woodland understory:

Often herbaceous perennials with a low growth habit, which take advantage of higher light levels in winter and/or spring when trees are leafless.
Winter and spring growing geophytes (such as those which produce bulbs or corms) produce flowers and leaves in winter or spring, going dormant through summer when they survive via an underground storage organ.
Some evergreen or semi-evergreen woodland herbaceous perennials complete a flush of growth and flower in spring, then go dormant through summer when they retain their leaves but do not put on active growth.

3. Describe garden situations that would best replicate each of the habitat types named in Q1.

Alpine: green roof's, troughs and planters with well-draining growing media, cracks in dry stone walls.
Mediterranean: south facing beds and open areas that receive direct sunshine, particularly on soils with a high sand content, which are freely draining and quickly become dry in summer.
Woodland understory: beneath deciduous trees, shrubs and hedgerows; in shaded sites, e.g. north facing beds that don't receive direct sun.