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structure of woody plants (secondary xylem (growth rings (Tree rings grow…
structure of woody plants
vascular cambium
initation of vascular cambium
secondary growth begins from here by producing additional xylic and phloic tissues.
interfascicular cambium
present between to vascular bundles.
fascicular cambium
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the portion of vascular cambium that grows within a vascular bundle
Fusiform initials
elongated tapering cells thats gives rise to all cells to a vertical system of secondary pholem and xylem.
Ray initials
the short and cubodial cells that gives rise to ray of the secondary xylem and pholem
storage parenchyma and albuminous cells
typically grouped in short vertical rows
arrangement of cambial cells
divides to produce secondary xylem cells towards the central axis of the stem and secondary pholem cells towards the outside cells.
secondary xylem
types of wood
heartwood
dead and innerwood which compromises the majority of the stem cross-section.
dark color
sapwood
living and outermost portion of the woody stem or branch
lighter color
growth rings
Tree rings grow under the bark, and the bark is pushed out while the tree is growing.
The inner part of a growth ring is formed early in the growing season, when growth is fast and is known as early wood.
The outer portion is the late wood, and is denser than early wood.
helps us to find out how old is tree, growth, weather.
types of woods cells
ray parenchyma
logitudinal tracheids
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wood cells are equipped with pits
reaction wood
characteristic wood formed as part of the gravitropic response of trees and shrubs, and generally occurs in leaning stems including branches
In conifers, reaction wood is known as compression wood while in hardwoods it is known as tension wood.
formation that occurs after the vascular cambiums secondary growth.
this type of xylem is not present in non-woody plants, but commonly seen in shrubs and trees.
consists of large size vessels and tracheids
secondary pholem
it is formed from the vascular cambium during secondary growth.
transports nutrients throughout the tree or woody plants.
is located beside the bark.
the annual growths rings are thin in this section.
outer bark
lenticles and oxygen diffusion
In plant bodies that produce secondary growth, lenticels promote gas exchange of oxygen, carbon dioxide, and water vapor.
As stems and roots mature lenticel development continues in the new periderm (for example, periderm that forms at the bottom of cracks in the bark).
Initation of cork cambia
consists of lignified pholem tissue following stripping
cork and cork cambium
cork cambium is like the vascular cambium, a lateral meristem that produces cells internally and externally by tangential divisions.
cork originates from a layer of cambium that itself is formed as secondary meristem from a layer of collenchyma or parenchyma immediately beneath epidermis.
also called phellogen
function of cork cambium is to produce the cork, a tough protective material.
anomalous forms of growth
unusal primary growth
anomalous secondary growth
Most anomalous growth is associated with the formation of multiple cambia.`
An increase in plant girth due to vascular cambium or cork cambium is called secondary growth. As a result, the secondary plant structures that are formed are termed anomalus.
secondary growth in roots
supporting root structures produce by lateral meristem,vascular cambia and cork cambia.
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unobserved underground root systems of most trees are as massive as the huge aerial bodies and counterbalance the aboveground weight thus keeping the tree upright and stable.
initation of secondary growth takes place a zone of maturation soon after cell stops elongating there.
both are combined to form wood tissue
both are made of meristematic cells
