Leaves and plant form/function Flashcards
(36 cards)
Describe bryophyte leaves?
Liverworts don’t have leaves. Mosses are different leaves to the other land plants – they are more tolerant of desiccation than most other leaves on land plants.
Describe fern fronds?
Fern fronds are different in the way that the sporangia (which produce the spores) are produced on the fronds.
Describe gymnosperm leaves?
Pine needle is a half way structure between a shoot and a leaf.
Describe angiosperm leaves?
A leaf is described as a structure that grows from a stem and where the structure meets the stem, there is a bud.
Types of leaves?
- Microphylls – single leaf trace (vein)
- Eudicot megaphylls – multiple leaf traces (veins) in a reticulate (networked) pattern
- Monocot megaphylls – multiple leaf traces (veins) in a parallel arrangement pattern
Why are the leaves of Monstera deliciosa fenestrated?
Possible reasons included reducing wind resistance, let water through, reducing herbivory, letting light through or this species is bad at making leaves.
Why are younger leaves coloured differently?
Could be to reduce herbivory or UV damage, or might just be part of development. Unknown why leaves change colour in autumn.
How do plants deal with water stress?
Discarding leaves to limit transpiration losses or making drought resistant leaves. Can happen due to drought or v cold temperatures freezing the soil.
How do plants float on the surface of water?
Trap air… 1. In empty cells in leaf petiole (water lilies) 2. In between hairs (water lettuce) 3. In leaf lamina (duck weed) 4. In empty cells in the veins (Victoria water lily)
How many times have carnivorous leaves evolved?
At least 5. Example of convergent evolution. Despite all of these plants are unrelated and evolved independently, they all use the same enzyme to digest prey. What’s striking is that the same genes from non-carnivorous ancestors have been recruited for carnivorous purposes. Namely, proteins originally involved in protecting the plants against diseases and other stressors eventually turned into digestive enzymes. This ability likely appeared as a means for the plants to cope with nutrient-poor environments. Trapping and digesting animals can be indispensable in this situation.
Uses of scented leaves?
Attract animals such as pollinators Repel herbivores Inter-plant warning/communication.
Uses of hairy leaves?
Reduce water loss by evaporation Insulation Stinging hairs for protection
What are the different whorls of organs in flowers?
Calyx (sepals) Corolla (petals) Androecium (stamen) Gynoecium (carpel) Flowers can contain any number of these.
How can you tell if plants have fused petals?
Notches in the petals or find mutants with more petals (gene for fusing knocked out)
Example of the fact that not all tubes are petals?
Daffodil. Stamens are fused to the tube and the trumpet is an extension of the stamens. The tube is a tissue which joins together the stamens. Was more obvious in the relatives.
Define an inflorescence?
A bunch of flowers, usual to have multiple.
Which plants have a variable number of plant organs?
Magnolias are an example
How is pollen released from the anther?
Can split open and display all its pollen or pollen comes out of a small hole.
Define monoecious
One house – plants with either perfect flowers or with both male and female flowers on the same plant.
Define dioecious
Two houses – plants having staminate and carpellate flowers on separate plants.
Issues with pollination
Make sure that the pollen is taken to the same species of plant. Major issue if the pollinating animal dies out, as can’t pollinate certain flowers. Has potential to become incredibly self-inbred.
Types of pollinator?
Bird, moth and bee. Groups of flowers are normally pollinated by the same animal.
How is the correct stigmatic surface found?
Some species produce millions of pollen grains which are moved by the wind and statistically will pollinate another plant. Others use visual, olfactory and taste stimuli to attract an animal intermediary.
Non-biological pollination?
- Wind. Evolved many times and is the most common pollination syndrome. Not advanced, but not the primitive state. Pollen tends to be small, dry, smooth and non-adhesive. All British timber trees are pollinated by wind. Don’t need to attract wind. Some forcibly eject pollen. Birch catkins have flaps to prevent pollen falling out due to gravity – must be blown out. Lock and key mechanism of pollen recognition to provide water for germination. 2. Water Water pollination can result in premature germination by accidental absorption of water. Must be very waterproof pollen. Aquatic plants are rarely pollinated by water.
