An Introduction to Winter Botany

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An Introduction to Winter Botany
James E. Perry, PhD, PWS
Feb. 6, 2009
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Definition of Terms
Habit

Tree
Sapling
Forb/Herb/ Graminoids
Shrub
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Definitions of Habit
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Definition of Terms
Twigs

• Terminal portion of a branch which grew during
  the current year or preceding year.

• Stoutness, color, smoothness, round or angled in
  Xsection, corky ridges or thorns, spines or
  prickles.

• Thorns are shape-pointed modified branches
  spines are sharp, modified persistent stipules
  (usually paired), prickles are outgrowths from
  young bark and are usually scattered over the
  surface.

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Prickles
Armament
Spines - sharp, modified persistent stipules
(usually paired). Prickles - outgrowths from
young bark and are usually scattered over the
surface. Thorns - shape-pointed modified
branches.
Spines
Thorns
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Twigs
Spur shoots - slow growing twigs (characteristic
of Rosaceae and Aquifoliacea).
Lenticels -small dots or patches scattered over
the surface of twigs.
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Twigs
Pith - central portion of twig that is composed
of large, thin-walled cells. Look for color,
shape, robustness.
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Twigs
Leaf Scares -corky protrusion that forms at base
of leaves just before abscission. Look at shape,
size, arrangement
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Twigs
Bundle Scares point where vascular tissue
passed from stem to leaf. Look for number and
arrangement
Stipule Scares - found on many trees, but missing
on some, these are a small leaf-like appendage
attached at the base of the leaf petiole. Shape,
size, and length. (Note circular stipule scares
on Sycamore and Magnoliaceae)
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Buds
Formed in resting stage during the growth of the
tree and contain embryonic leaves or flowers.
May be protected by bud scales (modified leaf) or
scale-less (naked). Bud scales can be valvate
or imbricate.
Naked Bud
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Buds

• May be terminal or lateral, or lacking
  (pseudoterminal).

• When pseudoterminal, lateral buds then platy role
  of terminal buds.

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Special Cases
Oaks have one terminal and four lateral buds,
giving appearance of five terminal buds).
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Special Cases
American Beach has alternate sharp terminal buds
Members of Elm Family (Celtus, Ulmus) have
pseudoterminal buds that give them a zig-zag shape
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Special Cases
Only four species of trees have leaves/bud scares
Maple (Aceraceae)
Ash (Oleaceae)
Dogwood (Cornaceae)
Buckeye (Hippocastanaceae)
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Habitat
Note environmental site conditions Xeric Mesic
Hydric.
Note aspect, soil, slope, temperature.
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Twigs2
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Pith
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Fruit
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Fruit2
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Data Sources on the Web

• USDA Plants Database
• http//plants.usda.gov/plants/
• VT Forestry site http//www.cnr.vt.edu/dendro/den
  drology/factsheets.cfm
• Virginia Atlas http//www.biol.vt.edu/digital_atl
  as/

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Other Data Sources
National Plant List http//www.sac.usace.army.mil/
permits/national.pdf)
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Other Data Sources
Plant Synonymy http//www.sac.usace.army.mil/permi
ts/synonymy.pdf
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Other Data Sources
Key to Winter Twigs (http//www2.una.edu/pdavis/Tw
ig20Key.htm) In part, after Preston Wright's
Identification of Southeastern Trees in Winter
N.C. Agri. Exten. S. AG-42
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Fruit Terms
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