Exam 1 Part 2 Flashcards
herbaceous stems are organized into 6 areas:
epidermis
cortex
pith
primary xylem
primary phloem
cambium layer
stem epidermis
cells arising from protoderm; covered by cuticle
glabrous stems
without hairs, smooth and often shiny
pubescent stems
small epidermal hairs
cortex & pith
arise from ground meristem; may have starch reserves and structural roles
stem xylem
conduct water and dissolved minerals from roots to rest of plant
stem phloem
distributes food from photosynthetic tissue to other tissues
solenostele
present in some eudicots; vascular tissue appears as continuous ring
eustele
present in most eudicots; vascular bundles discrete but in a circle
atactostele
present in most monocots; vascular bundles scattered through stem
sieve cells
arranged end-to-end in columns; make up phloem tissue
companion cells
located next to sieve cells, keep sieve cells alive
xylem tissue
composed of water-conducting cells, fibers, and parenchyma cells
tracheids
found in all vascular plants, have thinner cell walls
vessel elements
found in angiosperms and gymnosperms, thick cell walls
vascular cambium has two types of cells:
fusiform initials and ray initials
fusiform intials
cells inside > secondary xylem
cells outside > secondary phloem
cells sideways > add more cells to meristem
ray initials
forms vascular rays
stem periderm
cork cambium’s three layers: phellem cells (outside), phelloderm cells (inside), meristematic cells (center)
zone of division
root apical meristem divides to create primary meristematic tissue
zone of elongation
newly divided cells grow longitudinally
zone of maturation
root hairs form and help absorb water and minerals
quiescent center
area of the RAM that divide at an extremely low rate
root primary tissues:
epidermis
cortex
vascular cylinder
pericycle
endodermis
inner layer of cortex; helps control mineral accumulation
casparian strip
waxy material embedded in the transversal and radial walls of epidermal cells
vascular cylinder
differentiates from procambium; consists of primary xylem, primary phloem, and pericycle
in eudicots, vascular tissue is…
X shaped in the center
in monocots, vascular tissue…
forms a ring around the central pith
protoxylem
first xylem element to mature
capable of transporting water while elongating
metaxylem
mature after cell elongation is completed
forms thick secondary walls for water and mineral transport
phloem
form in area between protoxylem arms
first part of vascular system to become functional
lateral root primordia
forms new cells
secondary phloem forms inner bark, pushing pericycle outwards and…
remaining pericycle becomes cork cambium
leaf blades increase…
surface area for photosynthesis
true leaves arise from
leaf primordia
guard cells
surround stomata and control opening size
subsidiary cells
support guard cells
trychomes
hairs that can secrete substances
in relaxed state, guard cells…
lie parallel to each other
when there’s no light…
stomata remain closed
palisade cells
differentiated from ground meristem
main tissue for photosynthesis
spongy cells
differentiated from ground meristem
allow diffusion of gasses from stomata
veins consist of vascular bundles that…
form a network of xylem and phloem
Hypogeous
Cotyledons underground
Epigeous
Cotyledons breach above ground
Main tissue systems
Ground tissue
Vascular tissue
Dermal tissue
Types of simple tissues
Parenchyma
Collenchyma
Sclerenchyma
Parenchyma cells
Thin primary cell walls
Perform metabolic functions (photosynthesis, storage)
Only type of cell that can be reprogrammed to form other cell types
Parenchyma tissue
Can aggregate to form tissues found in cortex and pith, mesophyll
Collenchyma cells & tissue
Alive at maturity
Often containing chloroplast
Cell walls composed of pectin and cellulose; thicken at the corners
Support for young stems and leaves
Outermost cells of cortex
Sclerenchyma cells & tissue
Dead at maturity
Made of fibers and sclerids
Fiber cells
Long, narrow cells with thick, pitted walls tapered at the ends
Aggregate into continuous cylinder arounds stems or form strands
Slerid cells
Can form sheets or be in small clusters
Vascular system tissues
Composed of: vessel elements and tracheids, fibers, living parenchyma cells, sieve-tube members, companion cells
Epidermis tissue
Single layer of cells covered in cutin
Epidermal tissue, guard cells, subsidiary cells
Trichomes
Trichomes
Outgrowths of one or more cells
Periderm tissues
Protective Loy ear that forms in older stems , and roots
Phellom, cork dead at maturity and phelloderm
