plant structure and growth Flashcards
developmental plasticity
the ability to alter form in response to its environment
plant organs
roots- rely on sugar produced by photosynthesis
stems
leaves
(shoots) reply on water and minerals absorbed by the root system
roots
anchor the plant
absorbing minerals and water
storing organic nutrients
taproot
one main vertical root that gives rise to lateral roots
adventitious roots
arise from stems or leaves
fibrous root
monocots, no main root
root hairs
absorbtion of water and minerals occurs
vast number incereases surface area
stem
organ consisting of:
alternating nodes- point of which leaves are attached
internodes: the stem segments between nodes
axillary bud
potential to form a lateral shoot or branch
apical bud
located near shoot tip and causes elongation of young shoot
apical dominance
helps maintain dormancy in most nonapical buds
rhizomes
horizontal shoot grows just below surface
bulbs
verticle underground shoots consisting of enlarged bases of leaves that store food
stolons
horizontal shoots grow along surface; allow asexual reproduction
tubers
enlarged ends of rhizomes or stolons, food storage
leaf
main photosynthetic organ
flattened blade and stalk called petiole which joins blade to node and stem
tissue
dermal-skin
vascular - fluid movement
ground- other function including photosynthesis storage an support
vascular tissue system
carries out long distance transport of materials between roots and shoots
xylem( water and minerals) and phloem (organic nutrients to roots)
water conducting cells of xylem
trachieds - align end to end to form long micropipes
vessel elements
dead at maturity
sieve plates
porous end walls that allow fluid to flow between cells along the sieve tube
each sieve tube element has a companion cell whose nucleus and ribosomes serve both cells
parenchyma cells
thin and flexible walls
least specialized
perform metabolic functions
collenchyma cells
grouped in strands and help support young part of the shoot
thicker and uneven cell walls
often mechanical support for young and growing parts
sclerenchyma cells
highly specialized for mechanical rigidity
thick secondary walls
often dead at maturity- xylem cells
meristems
embryonic tissue and allow for indeterminate growth
apical meristem
located at tips of roots and shoots and at the axillary buds of shoots
primary growth
apical meristem elongates shoots and roots
root tip is covered by root cap, which protects the apical meristem
growth behind root tipL
division
elongation
maturation
secondary growth
lateral meristems adds thickness to woody plants
adds girth to stems and roots in woody plants, consists of tissues produced by the vascular cambium and cork cambium
characteristic of gymnosperms and many eudicots but not monocots
vascular cambium
adds layers of vascular tissue called secondary xylem (wood_ and secondary phloem
cork cambium
replaces epidermis with periderm, which is thicker and tougher
primary growth of roots
produces epidermis, ground tissue and vascular tissue
ground tissue fills cortex, the region b/w the vascular cylinder and epidermis
stele
vascular system of a root or a stem
angiosperms- stele of root is organized into a vascular cylinder
endodermis
innermost layer of the cortex
pericycle
where lateral roots arise from, outermost layer of the vascular cyliner
primary growth in shoots
shoot apical meristem is a dome shaped mass of dividing cells at the shoot tip
leaves develop from leaf primordia along the sides of the apical meristem
axillary buds develop from from meristematic cells left at the bases of leaf primordia
tissue organization of stems
lateral shoots develop from axillary buds on the stems surface
eudicots, vascular tissue consists of vascular bundles that are arranged in a ring
monocots, scattered throughout the tissue
vascular tissue of leaf moves sugar to the rest of the plant
tissue organization of leaves
epidermis: reduces water loss
stomata: allows CO2 EXCHANGE B/W AIR AND PHOTOSYNTHETIC CELLS
guard cells - at the pores
mesophyll, ground tissue of leaf
palisade mesophyll and spongy mesophyll
palisade is the upper part
