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Chapter 9: Structure of Woody Plants - Coggle Diagram
Chapter 9: Structure of Woody Plants
Concepts
From the meristems are derived sets of tissues: epidermis, cortex, vascular bundles, pith, and leaves. These are all
primary tissues
the account for the primary plant body.
Secondary tissues
- Constitutes the plant's secondary body. Made of wood (secondary xylem) and bark (secondary phloem and cork)
Woody plants Become taller through growth by the apical meristem's and wider by accumulation of wood and bark. Wood and bark contain conducting tissues, their accumulation gives plants a greater capacity to move water and minerals upward and carbohydrates downward. This causes an increase of leaves and roots.
Disadvantages- Expensive metabolically to construct Wood and bark. Most woody plants do not reproduce until they are several years old.
All pro vascular cells have differentiated into either primary xylem or primary phloem. Capacity is correlated with the needs of leaves and roots.
If a plant produces many leaves, the water loss is greater causing some or all of the leaves to die.
Adventitious roots
- Supply conducting capacity directly to the new section of stamping formed, thus bypassing older portions of stem. These plants must remain low enough for the roots to reach the soil
A woody plant is a combination of primary and secondary tissues: the tips of stems and roots and leaves, flowers, and fruits are herbaceous and primary. Portions of stems and roots do not undergo secondary growth and become woody until they are older
Vascular Cambium
The
Vascular cambium
Is one of the meristems that produce the secondary plant body.
The tips of roots and stems initially contain only primary tissues; however, at some time after metaxylem and metaphloem Had matured, a
vascular cambium
arises, containing primary and secondary tissues.
Can rarely form in leaves, but never in seeds, fruits, or flowers
Fascicular cambium
- When the cells continue to divide instead of maturing. Some mature parenchyma cells Between vascular bundles come out of cell cycle arrest and resume mitosis, forming an
interfascicular cambium
Fusiform initials
- long, tapered cells. When undergoing longitudinal cell division with a wall parallel to the circumference of the cambium (a periclinal wall). it produces two elongate cells. 1 cell continues to be a fusiform initial, the other secondary xylem or phloem.
Vascular cambium cells occasionally divide longitudinally over
anticlinal walls
(perpendicular to the cambium's surface), increasing the number of cambial cells.
Fusiform initials maker and regular horizontal rows, storied cambium, or a regularly without any horizontal pattern, non-storied cambium.
Secondary Xylem
All cells formed to the interior of the vascular cambium develop into
secondary xylem
, known as
Wood
Xylem contains all of the types of cells that occur in primary xylem but no new ones. Wood may contain tracheids, vessel elements, fibers, sclerieds, and parenchyma
An
axial system
is derived from the fusiform initials and a radio system develops from the
ray initials
The axial system always contains tracheary elements which carry a longitudinal conduction of water through the wood
Hardwood
- A term used for word of all basal angiosperms and eudicots.
Softwoods
- Wood from conifers such as pawns in redwoods I have few or no fibers in the service of the consistency. In many instances they're actually much harder than many hardwoods
The center of a log is almost always darker in color than the outer wood. This dark wood is
heartwood
and the lighter outer region is
sapwood
. The different regions exist because vessels and tracheids do not function forever and water conduction. Water columns break due to freezing, bugs, etc.
Sapwood turns into dark wood and is replaced approximately every year.
Reaction wood
- If branches or trunks have stress due to gravity the branch will droop and become pendant. This is a response to that. known as tension wood in angiosperms
Ray parenchyma cells store carbohydrates and other nutrients during dormant. And conduct material over short distances radiantly within Wood
The two basic types of Ray parenchyma cells are
upright cells
and
procumbent cells
.
procumbent cells- Have no direct Connection with axial cells, but upright cells do
Growth rings
Vascular cambium becomes active and begins cell division. At this time the new expanding leaves are thin and delicate and their cuticle is not as thick now fully polymerized
The first wood formed is
early wood
Also called Springwood and it must have a high proportion of white vessels and or wide tracheids.
Late Wood
Has a lower proportion of vessels and has a thicker cuticle. Transpiration is less and large numbers of newly formed vessels are conducting rapidly.
These two words together make up one year's growth also known as an
annual ring
. However the tree may fail to grow and produce a ring if it is unusually cold during the summer time. Because of this some people prefer the term
growth ring
Secondary Phloem
secondary phloem
- Formed from the vascular cambium just a secondary xylem is. It also has an axial and a radial system
The axial system is responsible for conduction up and down the stem or root.
This size, shape, and number of phloem rays match those of xylem raise because both are produced by the same ray initials. Phloem rays consist only of parenchyma cells that are used for storage, as are xylem rays
Outer Bark
Cork Cambium or phellogen
- As circumferential stretching increases and the older sieve elements die, Some storage parenchyma cells become reactivated and undergo cell division. This is similar to the activation of parenchyma cells during formation of the interfascicular vascular cambium but in secondary phloem it results in a new cambium
Cork cambium- All of it sells or cuboidal, like Ray initials. After division the inner soul almost always remains cork cambium where is the outer so differentiates into a
cork cell or phellem cell
It also may produce a seller two to the inside that mature into a layer of parenchyma called
phelloderm
Cork cambium, the layers of cork cells, and the phelloderm are known as
periderm
All tissues outside the innermost cork cambium comprise the
outer bark
. All secondary flowing between the vascular cambium and the innermost cork cambium is the
inner bark
Secondary Growth in Roots
Roots of conifers and woody angiosperms undergo secondary growth, as to the stems. The new vascular cambium has the same star shape as the primary xylem, but it's in becomes around as the cambium in the sinuses of the primaries that one produces more secondary xylem then do the regions of cambium near the arms of Protoxylem
Root vascular cambium contains growth rate in fusiform initials
Typically the word of roots is not the same as the stem. The type of wood is based off the conductivity requirements of each.
Anomalous Forms of Growth
Anomalous secondary growth
- Alternative cambia produce secondary bodies that differ from the top common type
Columns of some of the parenchyma cells undergo rapid division and produce nearest cells that differentiate into
secondary vascular bundles
A selective advantage of producing so many vascular cambium is that it may be the rate of cell production is important. The route must become large very quickly having just one cambium may be too slow. Multiple Cambia all functioning simultaneously speed the production of storage capacity
In several Eudicots, The vascular cambium of the common type arises and produces ordinary secondary xylem and phloem. After short. The cambium so stop dividing and differentiate into xylem.
A New vascular cambium arises in the outermost second floor on and so on. This type of secondary phloem is called
included phloem
. This might be advantageous because it protects the phloem from insects and other pests by one to several layers of wood
