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Chapter 8: Structure of Woody Plants (Secondary Xylem/Wood (Growth Rings,…
Chapter 8: Structure of Woody Plants
Vascular Cambium
located between metaphloem and metaxylem
fasicicular cambium
interfasciclular cambian
Ray Initials
produce short cells
storage parenchyma
albuminous cells in gymnosperms
undergo periclinal cell division
remains cambian ray intital
xylem parenchyma (inner cell)
phloem parenchyma (outer cell)
Fusiform initials
long, tapered cells
perciclinal wall
produces two elongate cells
continues to be fusiform initial
secondary xylem or phloem
thin primary walls
plasitids present as proplastids
phramoplast
anticlinal walls
divide cambium longitudinally
produce elongate cells of wood
tracheids
vessel elements
fibers
produce phloem
sieve cells
sieve tube members
campanion cells
fibers
Secondary Xylem/Wood
axial system
derived from fusiform initials
tracheary elements
very rare to find fibers/parenchyma
radial system
derived from ray intials
ray parenchyma
upright cells
procumbent cells
ray tracheids
secondary walls
circular bordered pits
protoplasts
Hardwoods
angiosperm woods
large amounts of fibers
eudicots
balsa
Softwoods
pines
redwoods
cypress
Growth Rings
Late (Summer) Wood
diffuse porous
vessels located throughout
Ring porous
vessels restricted to early wood
Early (Spring) Wood
Types of wood
Heartwood
Sapwood
Reaction Wood
Outer Bark
Cork Cambium (phellogen)
Cork cell
phelloderm
periderm
composed of tssues in the innermost cork cambian
Anomalous Forms of Growth
anomalous secondary growth
included phloem
unequal activity of vascular cambian
secondary vascular bundles
establishment growth
