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Woody Plants :deciduous_tree: (Secondary Xylem (reaction wood reaction…
Woody Plants :deciduous_tree:
Vascular Cambium
Fascicular Cambium
cells never mature
only when cambium is young
Interfascicular Cambium
mature parenchyma cells
only when cambium is young
2 cell types
Fusiform initials
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long tapered
longitudinal cell division
periclinal wall
anticlinal walls
ray initials
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short
cuboidal
periclinal cell divisions
Arrangement of Cells
ray initials
grouped together short vertical rows
fusiform initials
regular horizontal rows: storied cambium
irregular no horizontal pattern: nonstoried cambium
Secondary Xylem
types of wood cells
axial system
from fusiform initials
tracheary elements
carry out longitudinal conduction of water
fibers
strength/flexibility :muscle::skin-tone-3:
hardwoods
softwoods
radial system
from ray initials
parenchyma
arranged in rays
store carbohydrates
upright cells procumbent cells
trachieds
horizontal/rectangular cells
secondary cell wall
circular bordered pith
growth rings
early wood
high proportion wide vessels
first wood/spring wood
late wood
summer wood
lower proportion vessels
year older
larger
heavier
stronger
annual ring/growth ring
years growth
vessels throughout
diffuse porous
vessels restricted
ring porous
heartwood
dark wood
annual ring converted
sapwood
lighter
moister :sweat_drops:
new layer each year
reaction wood
response to stress
growth rings eccentric
gelatinous fibers with walls rich in cellulose
prevent from drooping
Secondary Phloem
axial system
conducting up/down stem/root
sieve tube members
companion cell
fibers and nonconducting parenchyma
radical system
parenchyma cells
storage use
Outer Bark
cork cambium/phellogen
cuboidal cells
creates cork cell/ phellem cells
matures into phelloderm
tissues outside outer bark
periderm
cork cambium
cork cells
phelloderm
impervious and tough
temporary protection
lenticels
align to permit oxygen across
aerenchymatous cork
Secondary Growth
roots
ray initials
fusiform initials
consist mostly of sclerenchyma
anomalous secondary growth
alternative cambia produce secondary bodies
included phloem
between bands of xylem
provides protection
unusual growth
established growth
palm trees :palm_tree: