Please enable JavaScript.
Coggle requires JavaScript to display documents.
Structure of Woody Plants (Secondary Xylem/Phloem (Growth Rings (Late wood…
Structure of Woody Plants
Vascular Cambium
Initiation of the Vascular Cambium
One of the meristems
Produce the secondary plant body
Fascicular cambium
Cells continue to divide instead of maturing
Interfasciular cambium
Connects on each side with the fascicular cambium
Unique in certain aspects
Two types of cells
Fusiform initials
Ray initials
Fusiform initials
Long, tapered cells
Undergoes longitudinal cell division
Periclinal wall
Produces two elongate cells
Vascular cambium cells
Anticlinal walls
Divide longitudinally
Increases number of cambial cells
Ray Initials
Similar to fusiform initials
Except they are short and cuboidal
Produce short cells
Mostly storage parenchyma
Arrangement of Cambial Cells
Ray and fusiform initials
Organized in specific patterns
Ray initials
Grouped together in short vertical rows
Usually only uniseriate, biseriate or multiseriate
Fusiform initials
Storied cambium
Nonstoried cambium
Secondary Xylem/Phloem
Types of Wood Cells
All cells formed to the interior of vascular cambium
Secondary xylem
Wood
Reflects that of the fusiform and ray initials
#
#
Axial stem, fusiform
Contain tracheary elements
Angiosperm
Contain large amounts of fibers
Hardwoods
Radial systems, ray initials
Conifers
Softwoods
Softer consistency
Ray parenchyma cells
Upright cells
Procumbent cells
Ray trachieds
Horizontal, rectangular cells
Growth Rings
Early wood
Spring wood
Must have high proportion of wide vessels, tracheids
Late wood
Cuticle has thickened
Transpiration is less
Many formed vessels are conducing rapidly
Summer wood
Lower production of vessels
Early and late wood
One years growth
Annual ring
Growing ring
Diffuse porous
Vessels located throughout wood growth ring
Ring porous
Vessels restricted to mainly to early wood
Hardwood and Sapwood
Heartwood
Dark wood in center of log
Sapwood
Light wood in center of log
Tylosis
Wood parenchyma cells adjacent to vessels
Push bubbles of protoplasm through pits to vessel
Forming a plug
Reaction Wood
In branches or trunks that are not vertical
Lateral stress
If not counteracted, branch would droop
Develops mostly on upper side of branch
Tension wood
Secondary phloem
Formed from vascular cambium
Axil and radical system
Outer Bark
Cork and the Cork Cambium
New cambium
Phellogen
Differs from vascular cambium
In both structure and morphogenic activity
After division
Inner cell remain cork cambium
Outer cell differentiates into a cork cell
Phellem cell
Phelloderm
Layer of parenchyma
Tissues outside of the innermost cork cambium
Outer bark
Secondary phloem
Inner bark
#
Lenticels and Oxygen Diffusion
Negative consequences
Blocks absorption of oxygen
Interfering with the respiration
Advantages
Keeps out pathogens
Retains water
Lenticels
Diffusion pathway for oxygen
Regions of aerenchymatous cork
Anomalous Forms of Growth
Anomalous Secondary Growth
Alternative cambia produce secondary bodies
Differ from the common type
Roots of sweet potatoes
Amount of storage parenchyma increased dramatically
Included phloem
Ordinary secondary phloem
Vascular cambium of the common type
Located between two bands of xylem
Unequal activity of the vascular cambium
Two sectors of the cambium are very active
While two are almost completely inactive
Stem becomes wider
Conducting capacity increases
Flexibility decreases
Secondary growth in monocots
Monocots don't have secondary growth like other plants
Anomalous secondary growth
Palms have an unusual type of primary growth
Columns of some parenchyma cells undergo rapid division
Secondary vascular bundles
Containing xylem and phloem
#
Narrow cells
Unusual Primary Growth
Palm trees
Trunks do not taper at the tips
Do not branch
Trunks are all primary tissue
Established growth
Increase in width and addition of adventitious roots
A form of primary growth
At some point this process ceases
