Chapter 7 - Leaves Flashcards
What are the basic parts of a leaf?
- Blade or Lamina
- Petiole
- Veins
- Stipules - usually small
- Abscission Layer - base of the leave that weakens and drops the leaf
- Axillary Bud -
- Leaf Gap
Hydrothodes
vascular bundle that is not plugged so it undergoes gluttation
Sessile Leaves
When the leaf blade is attached directly to the stem
Simple Leaves
They have only one blade. There are many shapes of blades, apexes, leaf bases, and leaf margins
Reticulate Venation
common for dicots with a network of veins. There are different vein patterns.
Reticulate Venation (Vein patterns)
- Palmate
- Pinnate
Parallel Venation
- typical in monocots
Dichotomous Venation
Veins spread out like a fan
Compound leaves
These leaves have more than one blade
Palmately compound.
- look for the axillary bud next to the petiole.
- several leaves from one petiole
- swelling at the base of the leaf.
example– blackberry
Pinnately compund
- it almost always has many leaflets
- can be bi or tripinnately compound
What are the leaf arrangments on a stem?
- Alternate
- Opposite
- Whorled
Three leaf tissue types
- Epidermis
- Mesophyll
- Vasular bundle
Epidermis
- has no chlorophyll
- secrete cutin to make a cuticle on the surface of the leaf
- ## has leave hairs
Three types of epidermal cells
- Typical
- guard cells - swell up when it takes in water. on the underside of leaves. guard cells include stomata
- Gland cells - projections that secrete things.
Mesophyll in dicots
- Palisade mesophyll - post-like cells that are tightly packed together.
- Spongy mesophyll - regulates the humidity
Mesophyll in monocots
don’t have different types of mesophyll
bulliform cells
huge, bubble-shaped epidermal cells found on the top surface of leaves in groups of multiple monocots. they store water.
tannins
tanned proteins that are denatured. Leaf turns brown of tan color
Carotenoids
Carotenes: yellow or orange
Xanthophylls: Pale Yellow
Anthocyanin, Betacyanin
anthocyanin = red
betacyanin = red
Why the change in color?
as the chlorophylls dissapear the other pigments become prominnat
Abscission Zone
when the leaf drops
The function is suppressed in the summer
it is triggered by day length
What are the layers in the abscission zone?
- Protective layer
- Separation layer
Sun vs Shade leaves
- Sunny leaves are thicker
Examples of leaves from shaded areas.
- Old man cactus
- Stonecrop
- Compass plant
Submerged aquatic plants
Tendrils
- yellow vetch
- rachis of a compound leaf
Spines
- stipules of the leaf makes the spine
- barberry
- black locust
storage leaves
Succulents
Stonecrop
Ice plant
- store water or food.
Reproductive leaves
buds on leaves that drop to the ground and start a new plant
example: Kalenchoe (air plany)
Bract
looks like a petal but it’s a leaf on Pointsetta
predatory plants
grow in acidic areas that are hard to get nitrogen
examples:
pitcher plants - secretes nectar by the rim and insects fall in.
Sundews - have glandular hairs that catch insects
Venus Flytrap - only grows in bogs by the Carolinas. has sensory cells
Bladderworts - form a chamber with a vacuum that sucks in insects
Butterwort - looks like melted butter on leaves. insects get stuck on
begonia leaf (blue)
looks blue
absorbs more green and red and less blue
structures slow down the light
What are human uses for leaves?
- Banana leaves for plates or protection
- food
- spices
- dyes - henna
- fibers - hemp, agave, palm trees
- oils - tea tree oil, lavender
Drugs from plants
- belladonna – atropine and scopolamine
- Foxglove – digitalis
- Tabacco
- Marijuana
- Caffeine
- Insecticides – bay leaves and neem tree
