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Structure of Woody Plants (concepts: (negatives to 2nd growth: (defenses,…
Structure of Woody Plants
concepts:
herbs only prim. plant body dev.
woody spec. addtl tiss prod
(prod stem&root from o meristem)
VC and CC
new tissues are wood&bark
wood=2 xylem
bark=2phloem and cork
these make up secondary body
combo of prim. & sec. tissue
woody plants have greater conducting cap.
negatives to 2nd growth:
defenses
energy to winterize
wood is expensive
energy not used to reproduce
years before reproducton
2nd growth occurs in:
gymnosperms
no ferns or monocots
basal angiosperms
eudicots
Vascular Cambium
initiation
cells between metaX and metaP
fascicular cambium in woody
2cambium form ring
ring called vascular cambium
extended yearly
rarely in leaves
never in fruit, flowers, or seeds
fusiform initials
long,tapered
divide longitudinally
2elongate cells
2nd X/2nd P
2nd X
2 more items...
fusiform initial
horizontal rows
or w/no pattern
ray initials
short, cuboidal
storage
albuminous cells
short, vertical rows
multiseriate
biseriate
uniseriate
stop dividing in herbaceous
parench cells do mitosis
form interfascicular cambium
connects to fasc. cambium
Secondary Xylem
contains all types as primary X
axial system from fusiform
tracheary elements
vert. conduction of water thru wood
softwoods
few fibers
hardwoods
many fibers
radial system from ray
only parenchyma
uniseriate
gymnosperms
biseriate
multiseriate
ray parenchyma cells
store carbs
move things short dist. radially
ray tracheids
growth rings
spring wood
high proportion of tracheids
summer wood
low proportion of tracheids
winter wood
no growth
annual growth ring
ring porous
diffuse porous
heartwood
tracheary elements don't work
sapwood
Outer Bark: Cork and Cork Cambium
new cambium in 2nd P
cork cambium (phellogen)
inner cell stays CC
sometimes produces phelloderm
CC+phelloderm=periderm
outer cell becomes cork (phellem) cell
encrusted w/suberin&dies
waterproof
outer bark
inner bark
initiation of CC
Primary P
2nd P
cortex
epidermis
