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Structure of Woody Plants (Vascular cambium (Arrangement of cambial cells,…
Structure of Woody Plants
Vascular cambium
Iniriarion of vascular cambium
vascular cambium
produce secondary plant body
fascicular cambium
old term for bundle
never undergo cell cycle arrest
interfascicular cambium
connects on each side of cambium
Fusiform initials
anticlinal walls
without, cells would be stretched
divide longitudinal
periclinal walls
longitudinal cell division
produces two elongate cells
long, tapered cells
Ray innitials
short, more less cuboidal
undergo periclinal cell division
one daughter cell strays back to become cambium ray initial
produce short cells
mostly just storage
Arrangement of cambial cells
storied cambium
irregularly
nonstoried cambium
without any horizontal pattern
ray initials
arranged in short vertical rows
one cell wide
fusiform initials
occur in regular horizontal rows
Secondary xylem
Types of wood cells
secondary xylem
contains
tracheids
vessel elements
fibers
sclereids
parenchyma
only real difference
origin and arrangement of cells
axial system
derived from fusiform initials
radial system
develops from ray initials
hardwoods
all basal angiosperm and eudicots
softwoods
sometimes much harder than hardwood
no fibers
from conifers
Growth rings
early wood
spring wood
high proportion of wide vessels
late wood
summer wood
lower proportion of wide vessels
annual ring
one year growth
growth ring
rings in truck of tree
can show age and growth of year
diffuse porous
vessels located throughout growth ring
ring porous
vessels restricted to early wood
Heartwood and sapwood
heartwood
dark wood
sapwood
lighter, moister outer region
drier wood
Reaction wood
known as tension wood
contains gelatinous fibers
Anomalous forms of growth
Anomalous secondary growth
alternative cambia
produce secondary bodies
roots of sweet potatoes
anomalous method of secondary growth
Ipomoea batatas
include phloem
located between two bands of xylem
unequal activity of the vascular cambium
Bauhinia
two sectors of cambium are very active
secondary growth in monocots
secondary vascular bundles
narrow cells that differentiate
Unusual primary growth
established growth
increase in width and addition of adventitious roots
palm trees
Outer bark
Cork and the cork cambium
phellogen
cork cambium
means new cambium
cork cell
aka phellem cell
outer cell
phelloderm
layer of parenchyma
periderm
cork cambium, layers of cork cell, phelloderm
outer bark
tissues outside innermost cork cambium
inner bark
phloem between vascular cambium and innermost cork cambium
Lenthicels and oxygen diffusion
lenticels
aerenchymatous cork
diffusion pathway for oxygen
keeps pathogens out
keeps water in
Initiation of cork cambia
arises before twig or root is one year
detectable as surface changes color
Secondary phloem
formed from vascular cambium
axial and radial system
axial
conducting up and down root system
