Leaf Adaptations

Question 1

What is a trichome?

Answer 1

A small hair or other outgrowth from the epidermis of a plant, typically unicellular and glandular.

Question 2

List 8 leaf adaptations

Answer 2

1. Hairs (trichome)
2. Essential Oils (Glandular trichome)
3. Upright orientation and reduced size
4. Thick waxy cuticle
5. Reduced stomata size or fewer stomata
6. Spines
7. Narrow leaves
8. No leaves

Question 3

How do hairy leaves protect the plant?

Answer 3

1. Reduce water loss
2. Provide resistance of air movement on leaf surface and stomata
3. Shade leaf
4. Reflect solar energy
5. Protects from insects/pests.

Stachys byzantina

Question 4

What is the use of glandular trichomes?

Answer 4

1. Essential oil on leaves
2. Deters insects/herbivores/pathogens

Lavandula angustifolia

Question 5

Adaptation of leaf and plant size?

Answer 5

Upright orientation and reduced leaf size.
Requires less water as reduced.

Question 6

Adaptation of stomata?

Answer 6

Reduced number of stomata size
Fewer stomata on the leaf
Sunken stomata

Less water evaporation

Question 7

What are Spines

Answer 7

Leaves that have adapted to minimize the surface area.
Succulent
Waxy cuticle
Sharp “teeth” at edges and tip

Stops animals from obtaining moisture from the plant.

Agave ovatifolia
Ulex europaeus (GORSE)

Question 8

Explain what adaptation narrow leaves have

Answer 8

Stomata is not exposed as it’s inside the leaf.
Inrolled margins - narrow gap at the bottom of the cross section.

EXAMPLE: Ammophila arenaria (marram grass)

Question 9

Do some plants have no leaves?

Answer 9

YES. These plants have adapted and have no leaves. They photosynthesize through their stems.

Cacti leaves are spines. Stomata is sunken and opens at night.

Succulents have collapsible cells which holds water.

Example: Genista spp. (Broom)

Opuntia microdasys has irritating leaves

Question 10

What is CAM

Answer 10

Crassulacean Acid Metabolism

Photosynthesis during day but stomata only open at night.

Plants have a slow metabolism

Plant stores C02 at night as malic acid, then can photosynthesize during the day.

Question 11

What is an Aerole?

Answer 11

Small raised cushion where spines and flower and branches grow.

Only found in a cacti (if NO aerole, not a cacti)

Oreocereus spp.

Question 12

How have some plants adapted to drought with examples?

Answer 12

1. Succulence: Ability to collect water (agave americana)
2. Spherical or columnar stems (Echinocactus grusonii)
3. Leaf spinescence of cacti (leaf=spine-aeroles)
4. Cacti pubescence (HAIRS) found in alpine area)
5. Root adaptations - spread far distances ( to absorb H20 quickly)
6. CAM

Question 13

How have aquatic plants adapted to their environment?

Answer 13

Roots are not needed to collect water used for anchorage only. They are thin and poorly developed.
Stems are flexible as held up by water
Thin or no waxy cuticle

Aeenchyma cells for buoyancy

Water pollinated

Question 14

What is aerenchyma

Answer 14

Modified parenchyma that form a spongy tissue creating air filled cavities that allow gas exchange within the plant and aid flotation in leave of aquatic plants.

EXAMP:ES:
Nymphaea alba
Trapa nutans
Nelumbo nucifera

Question 15

What does aerenchyma provide for the plant?

Answer 15

Buoyancy
Respiration

Nelumbo nucifera - lotus leaf. Held up by air spaces in stem.

Question 16

Submerged Leaves described

Answer 16

Thin and divided for large surface area
Flexible as water is moving
Stems leaves absorb nutrients
Thin or no waxy cuticle

Ex. Potamogeton. Pondweed

Question 17

Explain partly submerged leaves

Answer 17

Leaves floating
Generally large and wide
Leaves provide photosynthesis
Leaves encourage evaporation
Stomata high on leaf
Waxy upper epiderms to let water roll off and prevent algae forming
Very thin and wide leave to provide photosynthesis

Nymphaea alba

Question 18

Do aquatic plants have vascular systems

Answer 18

NO xylem or phloem as always surrounded by water.
Water is absorbed thru leaves and stems via osmosis.
Stems are flexible and thin.
Stomata is on top of leaf and always open.
Leaves retrieve gas from aerenchyma thru diffusion.

Question 19

Define Totipotency

Answer 19

The ability of a single cell to divide and produce the complete range of cell types that a plant requires.

African violet leaf propagation (RARE)
BULB: Can be sliced into sections (Base plate and scale leaves)

ONLY TISSUE WITH EXISTING CAMBIUM ARE TOTIPOTENT.

Question 20

What are leaf adaptations for dry conditions?

Answer 20

Silver/grey foliage: good variety colour
Subshrubs are short lived
Trichomes are inflammable?? REALLY?
Succulent SEDUM good for house and green roof
Wind and salt tolerant

Question 21

How are EG plants good in drought?

Answer 21

Physically tough leaves
Resistant to pests/disease (except buxus sempervirens)
PHOTOSYNTHESIS all year
Spiny plant - security hedge
Responds well with pruning
Dense twiggy foliage
Good contrast planting

Question 22

Evergreen and pest resistant

Answer 22

Leaf adaptations:
PRICKLY LEAVES: Tilia cordata - star shaped trichomes which are difficult for aphids to access.

Examples: Ilex aquifolium, Berberis darwinii.

Question 23

How does xlimate change affect leaf adaptation?

Answer 23

Leaf adaptation reduces need for water.
Rain gardens use aerenchyma for bog plants and water logging
Less water needed

Question 24

What is a variegated plant?

Answer 24

NOT a leaf adaptation. It is a mutation.
Has the absence of chlorophyll.
No waxy cuticle or hair.
Reduced photosynthesis.

Ilex aquifolium ‘Argentea Marginata’

Question 25

What is the horticultural impact of totipotency

Answer 25

cells can be used within micro-propagation, to produce a new plant. All forms are vegetative propagation.

Question 26

List some succulent examples with leaf adaptations.

Answer 26

To store water. Aloe vera Echeveria agovoides Kalanchoe blossfeldiana

Question 27

List advantages of uses leaf adaptation with oil

Answer 27

Reduces abiotic stress (water loss) Allelopathy: where one organism produces biochemicals that influence the survival, de and reproduction of other organisms (deters aphids) Defense against herbivory Repels viral vectors (aphids) Examples: Dictamnus albus Cistus ladanifer Tagetes patula

Question 28

How do hairy leaves help the environment

Answer 28

1. Trap airborne particles 2. Enhance plant resilience IMPACT: holds water on hairs for invertebrates 3. Keeps stomata safe from wind 4. Shades leaf surface 5. Reflects sun nrg 6. Keeps leaf surface cool

Question 29

What EG groundcover is good under trees (woodland floor)

Answer 29

Epimediums

Question 30

Explain adaptation to gain N for the plant

Answer 30

Insectivorous and Carnivorous plant. Eat insects to gain needed Nitrogen to survive as bogs have limited supplies.

Question 31

Name and briefly describe THREE leaf adaptations to dry environmental conditions, give an example of each:

Answer 31

a. TRICHOMES: The extension of the epidermis of a leaf that appears like hairs. This helps reduce water loss through the resistance of air movement over the leaf surface, reflects solar energy and provides some shade to the leaf. EXAMPLE: Stachys byzantina b. SPINES: Spines are leaves that have evolved to minimize the surface area of a leaf, protect the stems from predators seeking water and reduce the evaporation of water through transpiration. EXAMPLE: Agave ovatifolia c. NARROW LEAVES: Leaves that reduce the amount of water vapor loss through the stomata on leaves. Often leaves have inrolled margins to protect the stomata from exposure. EXAMPLE: Ammophila arenaria NOTE FROM TOM: Some needle like leaves also have sunken stomata which also reduces transpiration

Question 32

What is the primary advantage of being evergreen?

Answer 32

Where conditions allow: The ability to photosynthesize year-round Often resistant to pests and diseases Physically tough leaves

Question 33

what conditions might stop photosynthesis?

Answer 33

Too hot. Law of limiting factors

Question 34

Variegated foliage is common amongst garden plants. What causes variegation? Give an example of a variegated plant.

Answer 34

Variegation is a mutation, not an adaptation. The leaves have an absence of chlorophyll which will reduce the viability of the plant due to reduced photosynthesis. EXAMPLE: Ilex aquifolium ‘Argenteo Marginata’

Question 35

What are the advantages of a plant having silver leaves? And why might we be interested in growing such a plant?

Answer 35

a. Silver leaves help reflect solar energy, reducing both photosynthesis and transpiration of the plant. This leaf adaptation is advantageous in a dry/drought area as less water is required. b. The silver/grey colour provides an eye-catching garden design by adding a visual variation with the leaves of the different plants. Additionally, some silvery leaved plants have a pleasant odour to enjoy. EXAMPLE: Lavandula angustifolia

Question 36

Many plants have leaf adaptations that make them unattractive to being eaten by animals. Name THREE such adaptations with examples:

Answer 36

a. SPINES: A spine is a leaf adaptation which has evolved to minimize the surface area of the leaf as well as stiffen the plant. Often found on succulents and cacti. EXAMPLE: Agave ovatifolia b. ESSENTIAL OILS: Also known as a Glandular Trichome, it provides a defense against herbivores and viral vectors like aphids as they don’t like the smell/taste of the plant. EXAMPLE: Tagetes patula c. HAIRY LEAVES, Trichome; The trichome is an extension of the epidermis of the leaf. It has adapted to resist air movement, shade the leaf and reflect solar energy. Additionally, the hairy leaves tend to repel insects and animals. EXAMPLE: Rhododendron spp. When the leaves are young. As the leaves mature the hairy texture reduces.

Question 37

What are the kind of plants that you might consider planting around a car park? What do you think plants in this location need to achieve? Think about the advantages and disadvantages of various foliage types, and the various additional functions they might have in the landscape: visual interest, biodiversity. Frame your suggestions like this: large trees with dense foliage because….

Answer 37

a. Hairy, silver leafed perennial subshrubs, evergreen shrubs and grasses because a car park must remain a safe environment for cars/pedestrians with good visibility and protection. It is important that the plants in the car park provide a visually appealing view, security, biodiversity, but also provide , low maintenance and be drought tolerant. I choose these for the following reasons: i. HAIRY: hairy plants tend to trap airborne particles that are abundant in car parks. This will help reduce some environmental health risks for individuals. Hairy plants will also repel some animals which will help to maintain the plant. An example: Stachys byzantina ii. SILVER LEAVES: As car parks often do not have a watering system it’s a good idea to plant drought-tolerant plants that can withstand long periods of dry weather. Silver leaves reflect the solar energy reducing water needs. An example would be Lavandula angustifolia. This plant prefers poor, dry soil. Lavandula has pretty purple spike flowers that encourages bees and pollinators and also is visually appealing. It is a low growing plant so visibility remains sufficient for both pedestrians and cars. iii. EVERGREEN: To maintain the visual beauty of the car park, planting evergreen shrubs is a definite advantage. The leaves of evergreens tend to be physically tough and resistant to pests and diseases. As a security hedge, the Taxus baccata may be a good choice. Both pedestrians and animals will avoid the area. iv. GRASSES: Adding grasses to the carpark may add some visual diversity, provide structure but remain drought tolerant. The narrow leaves of grasses provide protection from drought and the stomata remains unexposed in the rolled leaves. An example: Ammophila arenaria. A very well-considered review. Correct to point out the range of factors and a good point re fruit (To which I would add pollen or resin). Good point re height, if you extend this point, if you were to grow tall growing trees you would have to access the site to trim them. Dense foliage correct and a very good point re spiky plants and pedestrian areas. Good work, well done A lot of very good work has gone into this, well done, thanks Steve