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Structure of Woody Plants, diffrence # # - Coggle Diagram
Structure of Woody Plants
Vascular Cambium
Initiation of the Vascular Cambium
secondary plant body
herbaceous location
metaphloem
woody species
fascicular cambium
interfascicular cambium
Fusiform Initials
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dicot (140-462)mm long
monocot (700-8700)mm long
undergoes longitudinal cell division
periclinal wall)
outer cell remains cambium cell
inner cell develops-secondary xylem
orientation
no exterior vascular cambium
no bark form on interior
Ray Initials
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periclinal cell divisions
inner cell is either xylem/parenchyma
fusiform initials produce the elongate cells of wood
storage parenchyma
Arrangement of Cambial Cells
storied cambium
nonstoried cambium).
forms as a narrow cylinder
single tree has single vascular cambial
Secondary Xylem
Types of Wood Cells
secondary xylem-wood
contains
tracheids,
vessel elements
fibers
Scelereid
parenchyma
reflects fusiform and ray initials
axial system
Growth Rings
early wood called spring wood
late wood called summer wood,
Late wood is stronger
contains numerous fibers/conifers
narrow, thick-walled tracheids
early and late wood together is anunual rings
1 year growth
cambium remain active continuously
Heartwood and Sapwood
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dark wood is heartwood
lighter, moister outer region is sapwood
tracheids do not function
water column breaks
reasons
freezing
wind vibration
wood-boring insects
no pulling water upward
water-filled tracheary elements produces next year
Reaction Wood
gravity causes a lateral stress
develops on upper side
Tension wood contains gelatinous fibers
fibers exert tension on the branch
less cellulose
gowth rings are wide on the lower side
Outer Bark
Cork and the Cork Cambium
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cells are cuboidal, like ray initials
differs from vascular cambium
phellem cell
mature parenchyma called phelloderm
Initiation of Cork Cambia
epidermis cortex are retained.
epidermis, cortex, primary phloem, or secondary phloem.
young stems differs from bark formed
reactivation of epidermal cells
secondary phloem
Lenticels and Oxygen Diffusion
Bark becomes permeable to oxygen
intercellular spaces penetrate the cork layer
produce only ordinary impermeable cork
lenticels do not run from the top
SECONDARY PHLOEM
axial system
conducts up and down the stem or root
angiosperms, or sieve cells in conifers
Radial system
innermost phloem do conduction
Secondary Growth in Roots
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Cambium same shape as xylem
woody angiosperm undergo secondary growth
interfasicular cambium
Anomalous Forms of Growth
Anomalous Secondary Growth
Roots of Sweet Potatoes
storage parenchyma is increased
Numerous vascular
cambia arise,
xylem and phloem produced parenchyma.
contain hundreds of cambia
Included Phloem
produces secondary xylem& phloem
no longer a cambium
oldest secondary phloem reactivated
advantage- protection of phloem
Unequal Activity of the Vascular Cambium
have equal actrivity
stem grows outward in two directions
advantage -flexibility
wider Bauhinia stem-
conductivity increases
Secondary Growth in Monocots
anomalous secondary growth
undergo rapid division and produce
narrow cells
Unusual Primary Growth
cambium never develops,
donot branch
distributed throughout ground tissue
true wood and
secondary phloem do not occur
trunk does not grow radially
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