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Structure of Woody Plants - Coggle Diagram
Structure of Woody Plants
Secondary growth in Roots
woody angiosperm undergo secondary growth
vascular cambium has the same shape as xylem
Vascularcambium arises just as the interfascicular cambium
Secondary Phloem
contains sieve tube members
the innermost layer of phloem is capable of conduction
Has radial or an axial system
It is former from the vascular cambium
companion cells in angiosperms or sieve cells in conifers
Secondary Xylem
Heartwood
the dark wood is the heartwood
the center of the log is always darker in color
center is usually more dry and fragnant
Sapwood
the lighter outer region is the sapwood
more moist and light in color
Reaction wood
gravity causes lateral stress
most of the plants produce lateral roots
found in branches or trunks that are not vertical
Growth Rings
after wood is produced, it's called the late wood
in strongly seasonal climates
annual ring can be seen after one year
cambium is quiscent during the time of the stress
cuticle is neither thick nor polymerized
Types of wood cells
Secondary xylem known as wood
Secondary xylem contains all kinds of cells
Hardwood
useful for construction
contains large amount of fibers
Radial system develops from ray initials
Soft wood
Has few fibers
Redwood, pines, etc
Outer Bark
initiation of cork cambia
arises before twig or root is even one year
it may arise in number of tissues
epidermis and ccortex are retained
timing of the initiation of the first cork cambium is variable
Lenticels and oxygen diffusion
interfering with respiration of the sapwood, vascular cambium
blocks the absorption of the oxygen
the bark becomes permeable to oxygen
keeps pathogens away and retains water
secondary phloem to be pushed outward
differentiation of secondary xylem causes the vascular cambium
innermost phloem cells form and mature
it contributes to the larger amount of stem or root
Cork cell
Matured layers called phelloderm
Also known as phellem cells
Vascular cambium
Fascicular cambium
an old type of bundle which divides plant cells
Ray Initials
store parenchyma cells
short
undergo periclinical cell divisions
more or less cuboidal
Interfascicular cambium
connects each side with fascicular cambia
Arrangement of cambium cells
occur in a horizontal row
non stored cambium
Organized in specific patterns
initials are grouped together in short vertical rows
Initiation of vascular cambium
produce secondary plant body
one of the meristem
Anomalous form of growth
Usual primary growth
distributed throughout the ground tissues
do not branch
Anomalous secondary growth
roots of sweet potatoes
most of the woody angiosperm are similar
activity of vascular cambia in conifers
alternative cambia produce secondary bodies