leaves Flashcards
basic parts
blade or lamina
lamina/blade
flat part of leaf.
petiole
base/stalk of a leaf… if not present, known as a sessile leaf (unstalked)
veins
thickened bundles of vascular tissue of the leaf
hydaphodes
open veins in a leaf, not plugged in the leaf.
examples: guttation from hydathodes, releasing water
stipules
small leaf at base of big leaf, can be estipulate if no stipule present
abscission layer
layer of cells at base of petiole, weakens and breaks during leaf drop season.
simple leaves
have only one blade…
reticulate venation
common for dicots, complex network of veins, some examples are palmate, pinnate,
parallel venation
parallel veins
dichotomous venation
dichotonous veination veins splitting
compound leaves
more than one blade, hard to distinguish compound leaves from a whorl: look for the petiole, look for axillary bud
pinnately compound
petiole continues as a rachus (extension of the petiole, contains leaflets)
alternate leaves
opposite leaves
whorled leaves
three types of tissue in leaves
epidermis, mesophyll, vascular tissue
epidermis of leaves
- single layer of cells all over the leaf,
- epidermis has no chlorophyll
- cells secrete cutin, which is used to make a cuticle on the surface of the leaf
three types of epidermal cells
typical
guard cell - swell up when taking in water, includes stomata
gland cell - secretes something, have different shapes
stomata
more common on the underside of the leaf, considered to be why there is more hair ot he bottom of leaf
floating leaves do not have on the underside, so they have stomata on the top of their leaves.
mesophyll cells in DICOTS
chlorenchyma cells
this is where photosynthesis takes place
- palisade mesophyll: tightly packed post like cells
- spongy mesophyll: moist, must be regulated because if dry out the stomata close.
mesophyll in MONOCOTS
dont have different types of mesophyll cells, bulliform cells line the inner shaft of mesophyll, if full of water the bulbiform will expannd and open up the leaf
leaves changing in the fall… tannins
occurs by different pathways…
- chlorophyll is broken down, chlorophyll is transported into the roots so that other colors can show through.
- simplest, which is brown, is drab.
- tannins give the tan protein, which gives tan / brown colored leaves.
tannins
-brown
carotenoids
- carotenes: yellow or orange
- xanthophylls: pale yellow..
anthocyanin, betacyani
not associated with photosynthesis, water soluble, found in vacuoles.
Anthocyanins are red
If alkaline, cell sap is blue.
if neutral, is intermediate color
betacyanin: red, less common, water soluble.
Can be in beets, cactus, amaranth
cell sap
material in central vacuolec
change in color
as chlorophyll goes away, can see other colors better.
abcission
preparing for and taking place of leaf dropping.
As leaf grows, special patch of cells in abcission zone function is surpressed in summer. Hormonally triggered changes in this zone,
separation layer
distal to protective layer, cells become weak, secrete proteins that breaks down middle lamella (which attaches cells together), so cells become loose from each other. After this happens, most of the petiole is no longer attached and vascular bundle hangs on loosely. When wind comes along, vascular bundle snaps and abcission takes place (leaf falls)
sun vs shade leaf
sun: leaves are thicker
shade: thinnder
leaves from arid areas
leaves reduced in size, (leaves can be spines), or thick/leathery to reduce water loss, reduced stomata
submerged plants
little xyla, not a lot of pallasaid perenchyma , underwater leaves may be dramatically different (smaller deeper in water, large leaves closer to surface), less vascular tissue
tendrils
modified leaves, support plant by wrapping, in grapes it is the stem
storage leaves
succulents
store water within leaves
iceplant (hottentot fig)
spines
stipules of leaf forms spines, barberry, black locus
reproductive leaves
kalenchoe: serrated edges of leaf, has babies between the edges, can drop these and they form their own life
bracts
specialized leaves associated with flowers often, may be leaf like,
pitcher plant
can capture prey (insects) that have nitrogen, predatory plant, secrete nectar near the rim and fluid near bottom. Insects fall in and cannot climb up the sides, digestive enzymes
sundew
has hairs that secrete sticky fluid, insects get caught, digestive enzymes digest insect
venus flytrap
only grows naturally in bogs of the carolinas. Hinged, leaves close to trap the fly
bladderworts
small aquatic plants, bumps have a chamber that is sealed and vaccuumed. If an insect touches it, a trap door opens and they get sucked inside to digest them
butterwort
leaves look like butter, insects get stuck there and get digested
begonia leaf
chloroplast reflects blue light, increase absorbance of green and yellow.
human uses for leaves
shade, photosynthesis, food, plates, protection, spices, dyes, fibers, (hemp, agave, palm tree), oils (tea tree, lavendar, eukalyptus, orange)
drugs
belladonna: atropine, scopalamine (sea sickness)
foxglove : digitalis, stimulates heart
tobacco: nicotine in roots,
marijuana: THC, CBD, oil
caffeine: insecticide, increases alertness, neuological effects, addictive to bees,
insecticides
bay leaves: repels pests
neem tree: has medicinal properties in the oil, indigenous people in india know about it, and did not want westerners selling it for profit
aesthetic
