Crooked Run Valley
Overview of Trees
Description of Trees
Plant Names (Scientific Nomenclature/Common Names)
Seventy-two species of trees, encompassing twenty-five tree families,
have been identified since the 2010 growing season. Field evidence
for additional species is currently being collected and studied.
The goal of the research conducted since 2010 has been to obtain an
accurate inventory of trees currently inhabitating Sky Meadows State
Park. This information provides an initial "baseline" for future field
research. Direct field observation was obtained for each identified
tree species. It is anticipated that additional species may be identified
during subsequent research and included in the field guide.
Every attempt has been made to achieve as accurate an inventory of tree
species as possible; however, several important caveats need to be kept
in mind when using the Nature Guide.
First, the inventory of trees included in the Nature Guide should not be
considered all inclusive. No assumption has been made that all the various
trees inhabitating Sky Meadows State Park were observed during the
2010 growing season. All trees included in the Nature Guide were observed
from the various Park trails; very limited off-trail research was conducted.
It is feasible that some species of trees may inhabitat areas of the Park
not readily accessible to the causal visitor. Since the purpose of the Nature
Guide is to provide visitors with information pertaining to the most likely
encountered species, most research has been conducted directly off the
main trails or within viewing distance from the main trails.
Second, the inventory of trees is a tentative list, not a final delineation.
The field research necessary to obtain accurate information for the
Nature Guide will require at least three years (2010 - 2012). It is
anticipated that additional species may be identified and incorporated
into the inventory, while modifications may be made in the current
status of individual species.
Third, while some tree species (e.g., tulip poplar) are very consistent
in morphological characteristics (e.g., leaf form), other tree species
(e.g., northern red oak) display a wide range of morphological forms for
a single characteristic (e.g., leaf form). It is not uncommon for the
variability of a single morphological characteristic of one tree species
to overlap with another, making identification of either species more
difficult. Often, several samples of a single morphological characteristic
is required to make an identification, and even then, absolute certainty
may not be feasible. In general, several samples of different characteristics
from a single tree will result in an accurate identification.
Fourth, a forest is a highly dynamic environment with evolutionary
tendencies in constant interplay. While nearly all tree field guides discuss
trees as if they were uniquely defined and identifiable living organisms,
this is generally not what is found during field research. Many species
of trees interbreed with other related species of trees, creating a "mixed"
or "hybridized" forest population, complicating the identification process.
For example, several members of the Genus Quercus (i.e., oaks) will
hybridize with each other, creating a broad mix of trees with combined
morphological characteristics. One of Sky Meadows more common trees,
the northern red oak, hybridizes with many oaks including scarlet oak
(Quercus coccinea), shingle oak (Quercus imbricata), swamp oak (Quer-
cus palustris), willow oak (Quercus phellos), scrub oak (Quercus ilicifolia),
northern pin oak (Quercus ellipsoidalis), black oak (Quercus velutina),
blackjack oak (Quercus marilandica) and Shumard oak (Quercus
shumardii). At this point in the field research process, it is not feasible
to ascertain the degree of hybridization that has occurred among the
tree species of Sky Meadows State Park. Keeping this in mind, all trees
are described as "pure" representations of their respective species.
Information for tree species was obtained from a variety of sources.
The Fire Effects Information System (FEIS) provided the "core" database
for most species information as well as general entry structure. Additional information from other sources has been "integrated" with the FEIS. Other
primary information sources include:
USDA Forest Service
FDGIF (Virginia Department of Game and Inland Fisheries)
VDF (Virginia Department of Forestry)
The general information format used by the Fire Effects Information System
(see "Databases" section of website for discussion of FEIS) is used for most
tree entries. Some modifcations in structure have been employed. The
following is a delineation of the modified FEIS format.
CITATION: The common tree name(s) followed by the current scientific nomenclature.
COMMON NAMES: List of generally accepted common names.
SCIENTIFIC SYNONYMS: Partial list of previously used scientific
CONFIRMATION STATUS: Two categories are used to determine the
status of confirmation - pending confirmation and confirmed. Pending
confirmation is assigned to a species that has either 1) been observed in
Sky Meadows Park but still needs formal identification by a recognized
authority or 2) has been observed on occassion but my not be established
in the park on a permanent basis. Confirmed is assigned to a species that
has both been regularly observed in Sky Meadows Park and has been
identified by a recognized authority.
TAXONOMY: Current taxonomic classification with discussion of
varities or subspecies, as well as hybridization characteristics.
NATIVE STATUS: Includes information pertaining to whether the
tree is native or introduced as it occurs in the United States and Canada.
GENERAL BOTANICAL CHARACTERISTICS: Includes information describing basic botanical characteristics (e.g., form, leaves, fruit, etc.).
REGENERATION PROCESSES: Regeneration from vegetative parts
and from seed.
SITE CHARACTERISTICS: Includes information on topography, soil
types and elevations where species occurs.
SUCCESSIONAL STATUS: Includes information on shade tolerance,
occurrences as pioneer and/or persistent species.
SEASONAL DEVELOPMENT: Flowering and fruiting dates.
GENERAL DISTRIBUTION: The general North American (United
States and Canada) distrubution of tree species.
SKY MEADOWS DISTRIBUTION: Distribution of tree species within
Sky Meadows State Park.
HABITAT TYPES AND PLANT COMMUNITIES: General habitat
types with emphasis on associated plant species.
IMPORTANCE AND USES: Importance of tree species to wildlife and
livestock, value for rehabilitation of disturbed sites, consturuction material
and ornamental use, and any medicinal characteristics.
Overview of Trees
A tree is a perennial woody plant. It is most often defined as a woody plant
that has many secondary branches supported clear of the ground on a single
main stem or trunk with clear apical dominance. A minimum height
specification at maturity is cited by some authors, varying from 3 m to
6 m; some authors set a minimum of 10 cm trunk diameter (30 cm girth).
Woody plants that do not meet these definitions by having multiple stems
and/or small size are called shrubs. Compared with most other plants, trees
are long-lived, some reaching several thousand years old and growing to up
to 115 m (379 ft) high.
Trees are an important component of the natural landscape because of
their prevention of erosion and the provision of a weather-sheltered
ecosystem in and under their foliage. They also play an important role
in producing oxygen and reducing carbon dioxide in the atmosphere, as
well as moderating ground temperatures. They are also elements in
landscaping and agriculture, both for their aesthetic appeal and their
orchard crops (such as apples). Wood from trees is a building material,
as well as a primary energy source in many developing countries. Trees
also play a role in many of the world's mythologies.
A tree is a plant form that occurs in many different orders and families of
plants. Trees show a variety of growth forms, leaf type and shape, bark
characteristics and reproductive organs.
The tree form has evolved separately in unrelated classes of plants, in
response to similar environmental challenges, making it a classic example
of parallel evolution. With an estimate of 100,000 tree species, the number
of tree species worldwide might total 25 percent of all living plant species.
The majority of tree species grow in tropical regions of the world and many
of these areas have not been surveyed yet by botanists, making species
diversity and ranges poorly understood.
The earliest trees were tree ferns, horsetails and lycophytes, which grew
in forests in the Carboniferous period; tree ferns still survive, but the only
surviving horsetails and lycophytes are not of tree form. Later, in the
Triassic period, conifers, ginkgos, cycads and other gymnosperms appeared,
and subsequently flowering plants in the Cretaceous period. Most species
of trees today are flowering plants (Angiosperms) and conifers.
A small group of trees growing together is called a grove or copse, and a
landscape covered by a dense growth of trees is called a forest. Several
biotopes are defined largely by the trees that inhabit them; examples are
rainforest and taiga. A landscape of trees scattered or spaced across
grassland (usually grazed or burned over periodically) is called a savanna.
A forest of great age is called old growth forest or ancient woodland (in the
UK). A young tree is called a sapling.
Description of Trees
The parts of an tree are the roots, trunk(s), branches, twigs and leaves. Tree
stems consist mainly of support and transport tissues (xylem and phloem).
Wood consists of xylem cells, and bark is made of phloem and other tissues
external to the vascular cambium. Trees may be grouped into exogenous
and endogenous trees according to the way in which their stem diameter
increases. Exogenous trees, which comprise the great majority of trees (all
conifers, and almost all broadleaf trees), grow by the addition of new wood
outwards, immediately under the bark. Endogenous trees, mainly in the
monocotyledons (e.g., palms and dragon trees), but also cacti, grow by
addition of new material inwards.
As an exogenous tree grows, it creates growth rings as new wood is laid
down concentrically over the old wood. In species growing in areas with
seasonal climate changes, wood growth produced at different times of the
year may be visible as alternating light and dark, or soft and hard, rings
of wood. In temperate climates, and tropical climates with a single wet-dry
season alternation, the growth rings are annual, each pair of light and dark
rings being one year of growth; these are known as annual rings. In areas
with two wet and dry seasons each year, there may be two pairs of light
and dark rings each year; and in some (mainly semi-desert regions with
irregular rainfall), there may be a new growth ring with each rainfall. In
tropical rainforest regions, with constant year-round climate, growth is
continuous and the growth rings are not visible nor is there a change in
the wood texture. In species with annual rings, these rings can be counted
to determine the age of the tree, and used to date cores or even wood
taken from trees in the past, a practice known as the science of
dendrochronology. Very few tropical trees can be accurately dated in
this manner. Age determination is also impossible in endogenous trees.
The roots of a tree are generally embedded in earth, providing anchorage
for the above-ground biomass and absorbing water and nutrients from the
soil. However, while ground nutrients are essential to a tree's growth the
majority of its biomass comes from carbon dioxide absorbed from the
atmosphere (i.e., photosynthesis). Above ground, the trunk gives height
to the leaf-bearing branches, aiding in competition with other plant species
for sunlight. In many trees, the arrangement of the branches optimizes
exposure of the leaves to sunlight.
Not all trees have all the plant organs or parts mentioned above. For
example, most palm trees are not branched, the saguaro cactus of North
America has no functional leaves, tree ferns do not produce bark, etc.
Based on their general shape and size, all of these are nonetheless generally
regarded as trees. A plant form that is similar to a tree, but generally
having smaller, multiple trunks and/or branches that arise near the
ground, is called a shrub. However, no precise differentiation between
shrubs and trees is possible. Given their small size, bonsai plants would
not technically be 'trees', but one should not confuse reference to the
form of a species with the size or shape of individual specimens. A spruce
seedling does not fit the definition of a tree, but all spruces are trees.