Secondary Body

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Topic 03
Secondary Body
Chap. 26 and the Info Box on Bamboo on p. 603 of
Chapter 25
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What is secondary growth?
3
Two meristems involved.
4

• I. Vascular Cambium
• Formation.

atactostele
euststele
Vascular Bundle Key Phloem Xylem Procambium
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• I. Vascular Cambium
• Formation.
• Where initials form from remnant procambium
• What periclinal mitoses

Fascicular portion
Interfascicular portion
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• I. Vascular Cambium
• Formation.

euststele
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• I. Vascular Cambium
• Formation.

euststele
8
Mostly periclinal, but anticlinal will be needed
too

• I. Vascular Cambium
• Formation.

euststele
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• I. Vascular Cambium
• Formation.
• When after 1o growth, towards end of 1st season
• Where in plant the older parts first

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B. Bifacial
1P
2P
1X
2X (aka wood)
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C. Annual Rings Rings of secondary xylem.
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C. Annual Rings
13
C. Annual Rings
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C. Annual Rings
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• Rays

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• Rays
• Composition Parenchyma mostly

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• Rays
• Function radial (rather than axial) transport.

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• Rays
• Gums, resins, metabolic wastes accumulate in
  center, which clog vessels tracheids, and may
  also discolor.

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• Rays
• Wood typically
• splits along rays
• as it dries.

Eastern Red Cedar
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• Rays
• In radial
• section.

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• Rays
• In radial
• section.

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• Rays
• In tangential
• section.

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Dialationof phloem rays due to anticlinal
divisions here, which extend the life of older
phloem

• Rays
• Xylem Rays
• Phloem Rays

From your book
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E. Fusiform Ray Initials
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E. Fusiform Ray Initials
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• Vascular cambium in roots
• Meristematic activity resumes in

1. Pericycle
and
2. Procambium
The root prior to secondary growth.
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• II. Cork Cambium
• Formation.
• Prior to
• formation
• epidermis
• intact.

euststele
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• II. Cork Cambium
• Formation.
• Rupture of epidermis necessitates Cork Cambium.

euststele
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• II. Cork Cambium
• Formation.

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B. Properties of Cork -suberin -dead -dermal
function -spongy
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C. Lenticels
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C. Lenticels
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D. Multiple Cork Cambia Layered
Periderms. Alternating layers of periderm
secondary phloem.
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III. Morphology of Woody Trunk
heartwood
sapwood
Wood
Bark
euststele
35
Horsechestnut
IV. Morphology of Woody Twig in Winter
2015 (yet to come)
2014
2013