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Woody Plants, Wood, Bark - Coggle Diagram
Woody Plants
Primary Growth
Gives us the procambium which gives way to the vascular cambium, and the cells that eventually become the cork cambium
All tissue derived from apical meristem (not to be confused with the apical bud, which is a structure of tiny immature structures and apical meristem)
Secondary Growth
Cambium
The lateral meristem that results in increase in width in "woody plants" subject to secondary growth.
Vascular Cambium
The procambium gives rise to the cells in the vascular cambium, in each vascular bundle
More cells somehow arise, and join with adjacent bundles to create a vascular cambium ring
This ring divides more inwards than outwards, because the cells inwards provide more structural support to grow taller and do not get crushed and cease to exist!
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Parenchyma cells (Rays) that run side to side and not up and down, they transport sugar, nutrients laterally, and help move compounds in.and out of heartwood. Visible
Cork Cambium
The ring of cells just below the epidermis become meristematic, representing the beginning of the cork cambium
these cells divide outwards to create cork cells in cork tissue, which is the outer part of bark. Cork cells are dead at maturing
cork has lenticels, or holes in the bark to allow exchange of gas and nutrients
Wood
Annual Growth Rings
Early Growth
After a period of dormancy when water and resources are scarce, these plants continue growing in spring, they produce larger (thin walled) xylem cells as water is more abundant. Appears light in the ring.
Late Growth
Towards the end of the growth season, the water levels available deplete which cause the tree to create small xylem cells (less to conduct) - These look darker because they are so dense, and end up marking the end of the year creating annual growth rings!
Late in the growing season, water is scarce, so the plant produces small, thick-walled xylem cells. Their narrow diameter increases adhesion and reduces cavitation risk, allowing water transport to remain stable under high tension.
Stress
A narrow ring means the cambium produced less xylem, which only happens when the tree is under stress.
The existence of the ring is guaranteed, but the visibility of the ring depends on conditions. You made need a microscope to see it: like if there is no contrast between the seasons in the rings. Dormancy is explicitly the cause of rings, as stopping and starting of cambium creates disconuity
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Sapwood
The outer xylem that conducts water, lighter
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