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structure of woody plants (vascular cambium (initiation of the vascular…
structure of woody plants
vascular cambium
initiation of the vascular cambium
vascular cambium: meristem that produces the secondary plant body
fasciccular cambium
interfascicular cambium connects on each side of fascicular cambium
2 cells types: fusiform/ ray initials
fusiform initials
long, tapered cells
undergoes cell division resulting in 2 elongate cells
fusiform and secondary xylem or phloem
grow with a wall parallel- periclinal wall
vascular cells divide longitudinally by anticlinal walls
thin primary walls, plastids present as proplastids
ray initials
short cells that stores parenchyma
undergo periclinal cell division
one daughter cell remains as cambium/ the other is xylem/phloem parenchyma
arrangement of cambial cells
ray initials: grouped together in short vertical rows only one, two cells, or many cells wide
fusiform initials may occur in horizontal rows (storied cambium), or irregularly without a pattern (nonstoried cambium)
secondary xylem
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types of wood cells
wood- secondary xylem
may contain; tracheids, vessel elements, fibers, sclerieds, and parenchyma
axial system develops from fusiform initials
always contains tracheary elements
helps move water through wood
radial system develops from ray initials
hardwood: contains a lot of fibers making the wood strong and tough
softwood- few to no fibers
harder than many hardwoods
growth rings
early wood- first wood formed
late wood
annual ring- early wood + late wood; 1 years growth
growth ring- tree fails to grow during harsh times producing a ring
diffuse porous- growth ring has vessels throughout it
aspen, yellow birch, sugar maple
ring porous- vessels restricted mainly to early wood
red oak,honey locust
heartwood and sapwood
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heartwood- center of log.,darker in color
annual ring is converted to heartwood each year
becomes wider with age
sapwood- center of log, lighter area
a new layer is formed each year via vascular cambium
less thickness
reaction wood
aka tension wood
outer bark
cork and the cork cambium
aka phellogen
all cells are cuboidal
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outer cell develops into cork cell
aka phellem cell
layers of cork cells and phelloderm are known as periderm
outer bark- outside of innermost cork cambium
inner bark- all secondary phloem between vascular cambium and innermost cork cambium
lenticles and oxygen diffusion
lenticels- regions of arenchymatpus cork
located at bases and cracks in bark
creates diffusion pathway for oxygen
initiation of cork cambia
detectable via surface color; green to tan
secondary of roots
growth around
anomalous forms of growth
anomalous secondary growth
alternative cambia produce secondary bodies that differ from the common type
unusual primary growth
palm trees; their trunks do not taper at the top like eudicots
establishment growth- increase in width and addition of adventitious roots
form of primary growth
secondary phloem
formed from vascular cambium
axial system responsible for conduction up and down stem/root
cork cambium cells are cuboidal like ray initials
this is an image of growth rings
this image shows phloem, xylem, and vascular cambium
the following image is a diagram of wood
Inner and outer bark contains secondary xylem/phloem
cork cambium makes up the trunk where heartwood/sapwood is found
