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Structure of Woody Plants (secodary xylem: Secondary xylem refers to the…
Structure of Woody Plants
Provascular tissue: Procambium
Fascicular cambium: cambium that develops within the vascular bundle
Pith: soft and spongy tissue
interfascicular cambium: cambium that develops between the vascular bundle
vascular cambium: meristem that produces secondary plant body
fusiform initials:The fusiform initials are elongated tapering cells that give rise to all cells of the vertical system of the secondary phloem and xylem
axial phloem
axial xylem
Ray initials: a cell in the cambium that gives rise to cells of the rays
phloem rays
cork cambium
cork: composed of phloem, cortex and epidermis. it is the outer layer of bark
Phelloderm: a layer of parenchyma produced inwardly by a phellogen
xylem rays
secodary xylem: Secondary xylem refers to the formation that occurs after the vascular cambium's secondary growth.
types of wood cells
axial system
derived from fusiform initials
consists of tracheids and trachery elements that conducts water
it also consists of fibers. the hardness of the wood depends upon the fibers it consists
radial system
deived from ray initials
Ray parenchyma cell
upright cells: these cells have connection with axial cells
procumbent cells: these cells have no direct contact with the axial cells
growth ring
a concentric layer of wood, shell, or bone developed during an annual or other regular period of growth.
ncrement of wood added during a single growth period.
Heartwood and Sapwood
Sapwood is the living, outermost portion of a woody stem or branch, while heartwood is the dead, inner wood, which often comprises the majority of a stem's cross-section.
heartwood is usually dark while sapwood is lighter in colour
main function of the heartwood is to support the tree.
brings water and nutrients up from the roots through tubes inside of the trunk to the leaves and other parts of the tree
Reaction wood
Reaction wood in a woody plant is wood that forms in place of normal wood as a response to gravity, where the cambial cells are oriented other than vertically.
found on branches and leaning stems.
Secondary Phloem : formed from vascular cambium
radial system run parallel to radii that pass through the center of the axis
axial system: does conduction up and down
the stem or root
Outer bark
cork and cork cambium
tissue in the stem of a plant that gives rise to cork on its outer surface and a layer of cells containing chlorophyll on its inner surface.
also called phellogen
all the cells are cuboidal
after division the inner cells remain cork cambium while the outer cell becomes cork. the inner mature cells are phelloderm and the outer mature cells are periderm
secondary growth in roots
the roots of conifers and angiosperms undergo secondary growth like that of the stems
the wood produced in the roots are similar to that produced in the stem
Anomalous forms of growth
roots of sweet potatoes
secondary growth in monocots
