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Structure of Woody Plants (Vascular Cambium # (Initation of Vascuar…
Structure of Woody Plants
Vascular Cambium
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Initation of Vascuar Cambium
Longitudinal Division
Periclinal wall
Fusiform initials
anticlinal wall
Long tapered cells
Periclinal Cell Division
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Ray initials
one continuous to be cambial ray initial
Other give rise to secondary xylem or phloem
Short Cubodial
Storage parenchyma cells
albuminous cell in gymnosperm
Extended each year
Cells do not undergo cell cycle arrest
Give rise to fascicular cambium
Continue to divide
Mature parenchyma cells comes out of cell cycle arrest
connects each side with fascicular cambium
Contains both primary and secondary tissue
Close to the tip of axes
near the ground
Younger
Oldest
Arrangement of Cambial Cells
Organized in specific patterns
Ray initials
Grouped together in short vertical rows
Can be
Multiseriate
Many cells wide
Uniseriate
one cell wide
Biseriate
two cell wide
Fulsifrom initials
regular horizontal rows
storied cambium
rare
occur in few eudicots species
tend to be door
irregular
non storied cambium
Secondary Xylem
Heartwood and sapwood
center usually drier and more fragrant
center is darker in color
inner layer is lighter
dark wood is heartwood
Lighter moisture outer region
Type of wood cells
Soft wood
Have few or no fibers soft as well
Such as pines and red woods
Hard Wood
Contains large amount of fibers
Useful for constructions
Growth Rings
First wood form is early wood also called spring wood
annual ring after one year
cambium is quiescent during times of stress
found in regions with strongly seasonal climates
Cuticle is neither thick nor fully polymerized
after wood produced called late wood
Reaction Wood
Branch would drop and become pendant
In branches or trunks that are not vertical
Gravity causes a lateral stress
most plants produce reaction wood
Secondary Phloem
innermost layer of phloem is for conduction
Axial system is responsible for conduction
Formed from the Vascular Cambium
It has an axial and a radial system
contains sieve tube members
Companion cells in angiosperm or sieve cells in conifers
Secondary growth in roots
Vascular cambium has the same shape as xylem
Woody angiosperm undergo secondary growth
Vascular cambium arises just like the interfascicular cambium
Anomalous form of growth
Anomalous secondary growth
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Alternative cambia produce secondary roots
alternative types of cambium structure and activity
activity of vascular cambia in conifers
Most are similar
Roots of sweet potatoes
Unusual primary Growth
Distributed throughout ground tissues
palm truck is a primary tissue consisting of vascular bundle
they do not branch
Outer Bark
Cork Cell
Also called phellem cells
Mature layer called phelloderm
Initiation of cork cambia
First cork cambium is variable
Subsequent cork cambia may form shortly afterward
epidermis and cortex are retained
arises before twig is even one year
may arise in a number of tissue
Lenticles and oxygen diffusion
Bark becomes permeable to oxygen
it blocks absorption of oxygen
Impermeability of cork has negative and advantageous consequences
it keeps out pathogens and retains water
interfering with the respiration of the sapwood, vascular cambium
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Types of connection
Types of connection
Functional Connection
Structural Connection
Mechanical connection
