Post by Icarus on Mar 23, 2008 21:49:10 GMT -5
TREES AND SHRUBS
North America has the world’s tallest trees, the most massive trees, and the oldest trees. It has nearly 60 kinds of oaks, some 35 pines, and more than a dozen maples. About 750 species of trees grow wild north of the Mexican border.
Exactly how many kinds of trees there are depends to a great extent on which plants are considered trees. One generally accepted definition of a tree is a woody plant with one erect stem (the trunk) reaching a height of at least 12 feet. Shrubs are usually shorter, with multiple stems springing directly from the ground.
Just as most people know instinctively what a tree is, so too are they aware that some trees have needles and others leaves. This is a useful starting point in tree identification, but one that requires refinement. For needles are actually leaves-long narrow ones that, like other leaves, contain chlorophyll, the green pigment required for photosynthesis. Trees with needles belong to the group of plants called conifers, which produce their seeds in cones. (Cedars, junipers, and other trees with scalelike leaves are also conifers.) Nearly all conifers are evergreen-that is, they are never totally without leaves.
Unlike most conifers, the majority of broad-leaved trees (such as maples and oaks) are deciduous in temperate regions, shedding their leaves before winter sets in. Another difference between the two groups is their mode of reproduction. Broad-leaved trees propagate by means of flowers and bear their seeds in fruits. Some broad-leaved species have separate male and female flowers, either on the same tree or on different ones.
Different Environments, Different Trees:
Conifers and broad-leaved trees have different distributions across the land. Conifers prevail in northern and western forests and in the South and Southwest. Regions with more temperate climates, richer soils, and to some extent greater rainfall support forests with a preponderance of broad-leaved trees, occur in intermediate areas.
Trees may belong to the same group yet have different growth requirements. Among the conifers, spruces are at home in cold, moist regions; firs can tolerate somewhat higher temperatures; pines do well in coarse, dry soils in sunny locations, especially where fires have produced competition from other plants.
Although certain pines and other species often grow in pure stands, trees are more frequently found in associations; that is, if one species is present, so are its “partners,” which do well under similar conditions. Oaks and hickories make up an association in several southern and central states; junipers and pinions, in arid parts of the West. Similarly, certain understory plants are characteristic of one type of forest. Vine Maples grow in the shade of northwestern conifers; Hobblebush, in mixed northeastern forests.
Such associations extend to birds or other animal life. Sapsuckers tap out holes in birch trees; Red Crossbills eat the seeds of various conifers. Relationships like these point out an additional benefit of sharpening your skills in tree identification: if you know which trees are in the vicinity, you can predict what other forms of life are likely to be around.
Some Identification Tips:
Leaves: First determine the general type of leaf-needlelike, scalelike, or flat and broad. Then look at the size, shape, texture, color, and arrangement. Most broad-leaved trees have leaves that alternate on a twig. (The Maples, with paired leaves are a major exception.) Some trees, such as hickories and the Boxelder, have compound leaves, with each leaf divided into leaflets.
Flowers: Large showy blossoms, such as those of the magnolias, often lead to precise identification of a broad-leaved tree. Such unflowerlike blossoms as birch catkins can tell you to which group a particular tree belongs.
Fruits: Closely related trees bear similar fruits, and so fruits can help you place a tree in a group or a particular species. Oak fruits, for example, are acorns and vary, according to species, in size, shape, and cup texture. Conifer “fruits”-cones-are also surprisingly varied. Check the size and look at the detail of cones lying on the ground; also look at their orientation on the branches. Fir cones grow upright; spruces; hang down.
Bark: Precise identification of a tree, especially in winter, may require a look at bark color, pattern, or texture, especially on the mature part of the trunk. If a tree has been identified as to a general type, the bark may suggest its specific name: Red Pine, Shagbark Hickory, Paper Birch.
Shape: The shape of a tree involves consideration of height, crown, width, the arrangement of branches, and other characteristics. The American Elm is usually called vase-shaped; it has a sturdy trunk divided into several major limbs, a broad crown, and arching outer branches. Shape varies with location. A forest tree, for example, will be taller and its crown narrower than the same species grown out in the open.
Identifying Needle-Leaved Trees:
White Pines:
Clusters of 5 pinyons (or fewer):
Needle length: 1-5 inches
Usually triangular in shape
Yellow Pines:
Clusters of 2-4
Needle length: 1-18 inches
Semicircular to triangular in shape
Larches:
Brushlike Clusters of 20 or more
Needle Length: up to 2 inches
Flat to Triangular in Shape
Yews:
Single clusters, usually appearing on sides of branches
Needle-length: One-half inch to 1 inch
Flat shape
Spruces:
Single Clusters, all around branches
Needle Length: up to 2 inches
Square or flattened in shape
Hemlocks:
Single clusters, on the sides of branches or all around the branches
Needle Length: Up to 1 inch
Flat shape
True Firs:
Single Clusters, on the tops and sides of branches
Needle Length: up to three inches
Flattened shape
Douglas Firs:
Single Clusters, on the tops and sides of branches
Needle Length: up to one and one half inches
Flattened shape
Redwoods/Baldcypresses
Single Clusters, on the sides of branches
Needle Length: Up to 1 inch
Flattened Shape
Taken from North American Wildlife
North America has the world’s tallest trees, the most massive trees, and the oldest trees. It has nearly 60 kinds of oaks, some 35 pines, and more than a dozen maples. About 750 species of trees grow wild north of the Mexican border.
Exactly how many kinds of trees there are depends to a great extent on which plants are considered trees. One generally accepted definition of a tree is a woody plant with one erect stem (the trunk) reaching a height of at least 12 feet. Shrubs are usually shorter, with multiple stems springing directly from the ground.
Just as most people know instinctively what a tree is, so too are they aware that some trees have needles and others leaves. This is a useful starting point in tree identification, but one that requires refinement. For needles are actually leaves-long narrow ones that, like other leaves, contain chlorophyll, the green pigment required for photosynthesis. Trees with needles belong to the group of plants called conifers, which produce their seeds in cones. (Cedars, junipers, and other trees with scalelike leaves are also conifers.) Nearly all conifers are evergreen-that is, they are never totally without leaves.
Unlike most conifers, the majority of broad-leaved trees (such as maples and oaks) are deciduous in temperate regions, shedding their leaves before winter sets in. Another difference between the two groups is their mode of reproduction. Broad-leaved trees propagate by means of flowers and bear their seeds in fruits. Some broad-leaved species have separate male and female flowers, either on the same tree or on different ones.
Different Environments, Different Trees:
Conifers and broad-leaved trees have different distributions across the land. Conifers prevail in northern and western forests and in the South and Southwest. Regions with more temperate climates, richer soils, and to some extent greater rainfall support forests with a preponderance of broad-leaved trees, occur in intermediate areas.
Trees may belong to the same group yet have different growth requirements. Among the conifers, spruces are at home in cold, moist regions; firs can tolerate somewhat higher temperatures; pines do well in coarse, dry soils in sunny locations, especially where fires have produced competition from other plants.
Although certain pines and other species often grow in pure stands, trees are more frequently found in associations; that is, if one species is present, so are its “partners,” which do well under similar conditions. Oaks and hickories make up an association in several southern and central states; junipers and pinions, in arid parts of the West. Similarly, certain understory plants are characteristic of one type of forest. Vine Maples grow in the shade of northwestern conifers; Hobblebush, in mixed northeastern forests.
Such associations extend to birds or other animal life. Sapsuckers tap out holes in birch trees; Red Crossbills eat the seeds of various conifers. Relationships like these point out an additional benefit of sharpening your skills in tree identification: if you know which trees are in the vicinity, you can predict what other forms of life are likely to be around.
Some Identification Tips:
Leaves: First determine the general type of leaf-needlelike, scalelike, or flat and broad. Then look at the size, shape, texture, color, and arrangement. Most broad-leaved trees have leaves that alternate on a twig. (The Maples, with paired leaves are a major exception.) Some trees, such as hickories and the Boxelder, have compound leaves, with each leaf divided into leaflets.
Flowers: Large showy blossoms, such as those of the magnolias, often lead to precise identification of a broad-leaved tree. Such unflowerlike blossoms as birch catkins can tell you to which group a particular tree belongs.
Fruits: Closely related trees bear similar fruits, and so fruits can help you place a tree in a group or a particular species. Oak fruits, for example, are acorns and vary, according to species, in size, shape, and cup texture. Conifer “fruits”-cones-are also surprisingly varied. Check the size and look at the detail of cones lying on the ground; also look at their orientation on the branches. Fir cones grow upright; spruces; hang down.
Bark: Precise identification of a tree, especially in winter, may require a look at bark color, pattern, or texture, especially on the mature part of the trunk. If a tree has been identified as to a general type, the bark may suggest its specific name: Red Pine, Shagbark Hickory, Paper Birch.
Shape: The shape of a tree involves consideration of height, crown, width, the arrangement of branches, and other characteristics. The American Elm is usually called vase-shaped; it has a sturdy trunk divided into several major limbs, a broad crown, and arching outer branches. Shape varies with location. A forest tree, for example, will be taller and its crown narrower than the same species grown out in the open.
Identifying Needle-Leaved Trees:
White Pines:
Clusters of 5 pinyons (or fewer):
Needle length: 1-5 inches
Usually triangular in shape
Yellow Pines:
Clusters of 2-4
Needle length: 1-18 inches
Semicircular to triangular in shape
Larches:
Brushlike Clusters of 20 or more
Needle Length: up to 2 inches
Flat to Triangular in Shape
Yews:
Single clusters, usually appearing on sides of branches
Needle-length: One-half inch to 1 inch
Flat shape
Spruces:
Single Clusters, all around branches
Needle Length: up to 2 inches
Square or flattened in shape
Hemlocks:
Single clusters, on the sides of branches or all around the branches
Needle Length: Up to 1 inch
Flat shape
True Firs:
Single Clusters, on the tops and sides of branches
Needle Length: up to three inches
Flattened shape
Douglas Firs:
Single Clusters, on the tops and sides of branches
Needle Length: up to one and one half inches
Flattened shape
Redwoods/Baldcypresses
Single Clusters, on the sides of branches
Needle Length: Up to 1 inch
Flattened Shape
Taken from North American Wildlife