|
Tree.
Typically has a single stem (trunk) at least 3 inches in diameter
at breast height (4 1/2 feet above the ground), a height of 12 feet
or more, and a single, rather well-defined crown.
Large tree.
Mature size of over 60' in height; often over 18” diameter.
Medium-sized tree. Mature height of 25 to 501; diameter
of 12 to 18”.
Small tree. Mature height mostly 12 to 20'; diameter rarely
over 10”.
Shrub.
Typically has smaller stature than a tree; usually with multiple
stems and a less-defined crown.
Vine.
Lacks a supportive trunk and climbs, sprawls, or creeps over other
plants or on the ground.
Groundcover.
May be a shrub or vine; prostrate on the ground or weakly ascending
above the ground; often obscuring the ground surface from view.
Colonial
(colony-forming) plants use underground stems called rhizomes
or elongated, running roots to send up many shoots. Such rhizomatous
or suckering plants may ultimately
form colonies or beds, all from the same original plant. Stands
of one species may be formed by rhizomes or root suckers, or be
due to heavy seedling germination in specific areas.
Juvenile
wood is found in all parts of young plants and sprouts,
and lower limbs of older plants. It has not yet reached the capacity
to produce flowers, and frequently exhibits foliage or twig characteristics
which may differ from that of normal older wood. Mature
wood includes branches and twigs which have reached reproductive
age. The drawings in the book Woody
Plants of the Blue Ridge, unless otherwise specified, show
features found on mature wood.
Form:
Twining.
Pertaining to vines; stems twist around objects for support.
Reclining or straggling, Leaning
or lying over other plants or other objects; weakly self-supporting.
Trailing. Elongating stems which
lie on the ground surface.
Fastigiate. Having a narrow
crown of slender, up-turned branches.
Woody vs.
Non-Woody:
Woody plants
are generally distinguished from non-woody or herbaceous plants
by the presence of woody stems — those remaining alive above
the surface of the ground throughout the year. Recognition of a
woody aspect is straightforward in the case of trees and large shrubs,
but not all plants fit so conveniently in the woody or non-woody
categories. Seemingly woody plants may die to the ground from radical
climatic fluctuations during Winter in one area or particular year,
or the same species may have woody stems in the southern parts of
its range and be herbaceous in the north. Deciding whether a rhizomatous
stem lying under leaf litter or a short, succulent stem qualifies
as a woody plant stem also serves to illustrate the rather arbitrary
nature of the woody plant category. Low-growing species like Chimaphila,
Epigaea, Gaultheria, Hudsonia, MitcheIIa, Pachysandra, and Sibbaldiopsis
are recognized as woody species by most people familiar with them,
but these and other herb-sized sub-shrubs and groundcovers may not
be so readily recognized by the beginner or student as belonging
to the woody plant category.
Tree vs.
Shrub:
The line of
separation between trees and shrubs is even less obvious than the
categories of woody vs. non-woody. While no problem may arise in
identifying most of our canopy species as trees and very low thicket-forming
species as shrubs, there is considerable middle ground. Many of
our understory species vary from "shrubby" to "treelike"
growth habits, depending on locale and other factors.... The obvious
shortcomings of the tree vs. shrub concept will be seen with prolonged
observation of many of our understory species, and the recognition
of objective opinion (and less concern with the importance of the
separation) of the tree vs. shrub category will inevitably be perceived.
|
