Unit 2 topic 1 Flashcards
State the primary purpose of leaves
To create food for the plant through photosynthesis
Describe the process that helps to cool the leaf in heat
In dry air, water vapour moves out of the leaf to try and equalise the humidity inside the leaf and the dry air outside it. Diffusion
Describe the leaf adaptation to reflect sunlight & 3 plants that have adapted to do this
silver hairs reflect strong sunlight
-Stachys byzantina
-Senecio cineraria ‘Silver Dust’
-Senecio candidans ANGEL WINGS (‘Senaw’ pbr)
What is a leaf adaptation against herbivory?
Prickly leaves. Ilex aquifolium
What is a leaf adaptation against water loss?
Reduced leaf area. Lavandula spp
What is a leaf adaptation against drought?
Thickened leaves to act as water storage. Aloe vera
What is totipotency?
Every part of the plant contains the genetic information to become any other part of the plant. DNA in the cell nucleus contains all the information to become any part of the plant tissue.
Why is totipotency important to horticulturists?
It makes cloning of specific traits/habits in plants possible. Cloning of desired plants from leaves, stems, roots.
List 5 purposes of the plant stem
- supports the plant
- Positions leaves in optimal place to capture sunlight
- Holds up flowers for pollinators
- Acts as a conduit between roots (where minerals and water are) to leaves
- Link between leaves (where food is manufactured) and all the growing parts of the plant (roots, shoots, flowers, fruit), where food is needed
Explain secondary thickening
In eudicots, the vascular bundles gradually join up to form complete rings with xylem on the outside and phloem on the inside. As the plant grows, a new layer of xylem is laid down inside the cambium. Year after year, new layers of x&p are laid down. The phloem pushes out and the xylem is compressed inwards and forms the ring within a tree trunk. The epidermis thickens and becomes corky protective bark.
Describe a stem defense adaptation
Short branches arising from auxillary buds evolve into thorns. Stops herbivory.
Pyracantha rogersiana
What are tendrils and twining stems?
Stems elongate and support themselves through other plants.
Lonicera periclymenum. Wisteria spp.
What are stolons?
Lateral stems that grow horizontally over the soil surface, producing adventitious roots at some nodes and adventitious buds and subsequently new plants along its length.
Fragaria x ananassa
Ranunculus repens
What are tubers?
organs formed at the end of rhizomes which store food over winter and develop into independent plants the following year.
Solanum tuberosum
What are runners?
Over ground stolons that only put down roots at its tip.
Rubus cockburnianus ‘Wyevale’
What are glandular hairs/ducts?
stems that contain essential oils that make them unpalatable to grazing.
Salvia nemerosa ‘Cardonna’
What is a stem adaptation against cold?
Stems are kept below ground so dormant buds are protected from cold damage in winter.
Anemone nemerossa (rhizome)
List 5 ways stems can be used for propagation
- Soft wood cutting taken from young material in active growth - Salvia
- Hardwood cuttings from longer sections of a one year old stem. Quercus
- Semi-ripe cuttings from deciduous material late summer through the autumn. Lavendula
- Layering producing roots when nodes on the branch or stems touching the ground. Cornus sanguinea
- Air layering by placing a wound in a stem and then wrapping in spaghnum moss to encourage new roots. The shoot is severed up to a year later and grows away on its on roots. Ficus elastica
What is the primary function of roots?
To take up water.
Also, to anchor the plant, bring in nutrients and help plants survive winter cold
What are fibrous roots?
In monocots. Multi-branched and occupying a large area in the upper top soil. Helps to prevent soil erosion. Ammophila arenaria
What are tap roots?
In eudicots. main roots that grown deep into the ground to source water and anchor the plant. Quercus alba
What are foraging roots?
Roots spread out over a wide area in the soil. Also fine hairs increase the surface area which can absorb water. Cacti
What is tropisms?
Growth movement in a specific direction. The radical emerges from the seed first and grows downwards.
What are adventitious roots?
Roots above ground. Stilt roots - Zea mays
Prop roots - Ficus benghalis
What are tubers?
Thickened lateral roots that have adapted to store nutrients over the winter. Dahlias
What are pneumatophores?
Roots that emerge above ground in water logged soils or bogs. Taxodium distichum
What are adventitious buds?
Develop from shallow roots creating ‘suckers’ Cornus or Rhus typhina
What are root nodules in legumes?
Rhyzobium bacteria enters through root hairs and causes cells to divide forming outgrowths or root nodules. The bacteria feeds off of sugars from the plant and also fixes nitrogen from the air so it is accessible by the plant.
What are aerial roots?
Roots that develop from a stem. They help support the plant in growing towards the sunlight. Hedera helix
Describe the symbiotic relationship between plants and fungi
Network of fungal filaments spread through the soil and reaching areas the plant roots cannot. They bring in nutrients like phosphorus in exchange for sugars produced in photosynthesis
How are roots used in propagation?
substantial one-year roots are cut into sections and inserted vertically into the soil (right way up!), thinner roots can be laid horizontally across the soil. The cuttings act as a food store, first new shoots and then eventually new roots are formed from the top of the cutting.
Describe a raceme
Flowers are attached to main stem by short stalks. Main axis continues to grow and produce flowers.
Example: Genista racemosa
Describe a corymb
All pedicels grow different amounts to reach the same level. Forms a platform for insects to land.
Example: Sambucus nigra
Describe a simple umbel
Pedicels arise from the same point.
Example: Agapanthus spp
Describe a panicle
Each branch is a raceme and on each the flowers open from the base of the raceme.
Example: Astilbe arendsii
Describe a cyme
The main axis forms a flower at its tip; then lateral buds form panicles of flowers which open from the top downwards.
Example: Begonia semperflorens
Describe a capitulum
Daisy-type flower: Showy ray florets attract pollinators to the fertile disc florets which are arranged in a mass for efficient pollen transfer.
Example: Helianthus annuus
Describe a verticillaster
whorled; flowers borne in rings at intervals up the stem, lower rings opening first. Tip continues to grow, producing more whorls.
Example: Stachys byzantina
What is the reason for flowering time adaptations in flowers?
To take advantage of pollinators available at the time of flowering and to attract the most pollinators in order to promote cross-pollination.
What is dichogamy?
When the stamens and stigma mature at different times on a flower.
What is protandry?
When the stamens ripen, produce and release pollen before the stigma of the flower is ready to accept pollen.
Example: Chamaenerion augustifolium
What is protogyny?
When the stigma matures first and is pollinated before the plant produces its own pollen.
Example: Magnolia grandiflora
Name a flower with ultra violet markings to attract bees
Alstroemeria spp
Name a flower that uses scent to attract pollinators
Daphne spp
Name a flower with nectaries
Tricyrtis formosana
What is a hermaphrodite flower?`
Perfect or entire. Having both male and female parts
What is an imperfect flower?
Having only male or female parts
What is a monoecious plant?
Having separate male and female flowers on the same plant.
Example: Juglans regia
What is a dioecious plant?
Male plants and female plants. Enforced cross-pollination.
Example: Ilex crenata
Define cross-pollination
Pollen from one plant lands on the stigma from another of the same species