Download (1) Tree growth - Wood Anatomy and Identification

WOOD 280
Wood Anatomy and Identification
Dr. Simon Ellis
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Softwoods
Hardwoods
Lodgepole pine
Hemlock
Aspen
Douglas-fir
Spruce
Birch
Oak
Maple
(Waddington arboretum)
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May 3
May 21
October 11
December 20
(Ellis)
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*
4
*
Tree trunk showing the successive concentric layers
Outer bark - dead tissue that protects the inner tissues from drying out, from mechanical injury and from insects
Inner bark (phloem) – conducts sugars produced by photosynthesis to the roots and other non-synthetic parts of the tree
Cambium – produces secondary xylem and secondary phloem
Sapwood – consists of xylem tissues through which water and minerals move from the soil to the leaves and other living parts of the tree
Heartwood – composed entirely of dead cells, supporting column of the mature tree
(St. Regis Paper Company)
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Sapwood - Heartwood
Sapwood
(Hoadley)
Heartwood
(Core, Côté & Day)
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earlywood
latewood
(Hoadley)
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(Haygreen and Bowyer)
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Three-dimensional representation of the vascular cambium
(Haygreen and Bowyer)
Cambial cell division
(Haygreen and Bowyer)
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*
Ontogeny of young
tree stem
c
d
e
pc
p
pp
px
vc
sp
sx
cortex
epidermis
epidermis
procambium
pith
primary phloem
primary xylem
vascular cambium
secondary phloem
secondary xylem
(Panshin and de Zeeuw)
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Cell development at apical shoot
Protoderm
Epidermis
Primary phloem
Apical
initials
Mother
cells
Procambium
Secondary
phloem
Vascular
cambium
Primary xylem
Cortex
Ground
meristem
Pith
Secondary
xylem
Representation of
developing stem
(Haygreen and Bowyer)
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Portion of a transverse section of a young stem showing arrangement of tissues
*
1.
2.
3.
4.
5.
1
2
3
4
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Mature xylem
Zone of xylem differentiation
Cambial zone
Zone of phloem differentiation
Mature phloem
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(Zimmerman and Brown)
Cell types and tissues associated with cambial activity
bark
mature phloem
maturing phloem
differentiating phloem
radially enlarging phloem
dividing phloem (phloem mother cells)
cambium
cambial initial (dividing)
dividing xylem (xylem mother cells)
differentiating xylem
radially enlarging xylem
maturing xylem
mature xylem
pith
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Periclinal division of cambial fusiform initials
(Haygreen and Bowyer)
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Anticlinal division of cambial fusiform initials
(Panshin and de Zeeuw)
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Formation of new ray initials in the vascular cambium
(a)
(a)
(b)
(c)
(d)
(e)
(f)
(b)
(c)
(d)
(e)
(f)
Initial a with extensive ray contact survives, while initial b with sparse ray contact matures into a deformed cell and
disappears
A ray is split by instrusive growth of a fusiform initial
A new ray initial arising from pinching off the top of a fusiform initial
Two single ray cells are formed through reduction of a short fusiform initial; either or both of these cells may survive and
later develop into rays consisting of a number of cells formed by subsequent division of these initials or they may be
eliminated
A new ray is formed by septation of the entire short fusiform initial
A new ray initial is formed on the side of a fusiform initial, which will continue to function as such
(Panshin and de Zeeuw)
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Plant Hormones – nature, occurrence and effects
Hormone
Chemical Nature
Sites of Biosynthesis
Transport
Primary Effects
Auxins
Indole-3-acetic
acid
Apical bud
Cell to cell,
unidirectional
(down)
Apical dominance
promotion of cambial
activity
Cytokinin
Phenyl urea
compounds
Roots tips
Via xylem from
roots to shoots
Cell division, delay
of leaf senescence
Gibberellins
Gibberellic acid
Young tissues of shoot
and developing seeds
Via xylem and
phloem
Hyperelongation of
shoots, induction of
seed germination
Ethylene
Ethylene
Most tissues in
response to stress,
during senescence or
ripening
By diffusion
from its site of
synthesis
Fruit ripening, leaf
and flower
senescence
Abscisic acid
Synthesized from
mevalonic acid
Mature leaves in
response to water
stress
Via the phloem
Stomatal closure,
induction of
photosynthate
transport
(Raven, Evert & Eichorn)
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Plant Growth Hormones
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