stems and roots Flashcards
function of shoot apical meristem
where mitosis occurs, protected by buds
leaf primordia
young leaf
axillary bud
found below the meristem, where lateral growth occurs
phytomere
area of growth
leaves function related to shoots
shoot protection
bud scales
small modified leaves that form a tight layer around the stem tip, protect dormant buds in the winter and have short or absent petioles
tunica-corpus organization
cells dividing in a perpendicular manner to each other in the shoot meristem
what happens to tissue layers as plant matures
they become more established
leaf trace gap
absence of vascular tissue
development of Monocot leaves
primordium becomes tubular and forms the sheating leaf base while upper portion forms the lamina
Fate of bud development
only some become a branch, others remain dormant or produce flowers
how is lateral growth prevented in plants?
hormone is produced at the apical meristem to enforce the dormancy of axillary buds
types of primary stem structure organizations
ground tissue = cortex
pith = parenchyma cells
narrow interfascicular region (vascular segments right next to each other) or wide interfascicular region
monocot primary stem structure vs dicot primary stem structure
vascular cylinders (dicot) or vascular bundles scattered (monocots)
large red cells in the middle of the dicot stem
xylem
stem function
structure, support, transportation, and conduction
leaf tendril vs stem tendril
if a bud is present, its a leaf tendril
herbaceous vines
modified stems that grow over things to get light
tallest tree in the world
coast redwood (Sequoia sempervirens)
storage bulb
stem is compressed, holds fleshy leaves (ex. onion)
storage corm
similar to bulb but had modified leaves
tubers
storage stems that are underground. Example is potato which is a stem full of parenchyma
how do stems do asexual reproduction
fragmentation
stolons and rhizomes
above and belowground stems function in asexual reproduction
storage rhizome
a type of specialized stem
cladophyll
specialized stems for photosynthesis (ex. asparagus)
types of stem modifications
prickles/spines/thorns
limitations of leaves
can’t lose too much water, can’t allow entry of pathogens, can’t be too nutritious to animals, must be cheap.
Cuticle
lipid and hydrocarbon polymers with wax and a bit of cellulose,
functions in water conservation and protection
where are stomata found in leaves?
found on lower epidermis of cross sections
where are chloroplasts
found in mesophyll
spongy mesophyll function
allows gas to move
stomatal crypts
stoma found in ‘indentations” of the leaf, helps reduce water loss
stomata opening and closing
based on environmental cues, and amount of stomata can change as well, potassium is involved
trichomes function
provide shade, prevent rapid air movement, make walking or chewing difficult for insects
bundle sheath
made up of fibers, arranged all around the vascular bundle, have their own photosynthesis
C4 plants v C3
C4: large bundle sheaths
C3: bundle sheath cells not as important in photosynthesis
abscission zone
area where cells are starting to get cut off, causes undamaged cells to become corky and form a protective leaf scar
mature plant abscission zone
has protective and separation layer
mesophyte
terrestial plants that grow in plants that aren’t wet or dry
has stomata on lower epidermis
hydrophyte
water plant but needs oxygen, so it contains aerenchyma (more spongey mesophyll), has stomata on upper surface, no cuticle, and leaf dimorphism
xerophyte
adapted to survive in an environment with little liquid water, contains thick cuticle, thickened epidermis, and stomatal crypts
succulent leaves
thick and fleshy, produced in arid habitats, reduced surface to volume ratios, favor water conservation, few air spaces in mesophyll
sclerophyllous
sclerenchyma as a layer below the epidermis and in the vascular bundles
perennial/evergreen leaves
hardness makes them highly protected
conifers
sclerophylls with thick cuticles, epidermis and hypodermis cells have thick walls, usually contain unpalatable chemicals, shapes may be needle like or flat and scale like
spines
needle sharp projections, protective and made primary of fibers
lignified walls make them hard and resistant to decay
tendrils
coil around objects and use them for support, growth is indeterminate, don’t typically photosynthesize
trap leaves
active traps that move during capture, passive traps incapable of movement
stipules
outgrowth of lower zone of a leaf
