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Species Guide
All text and photographs © 1996,1997
Thomas W. Kimmerer

Family: Aceraceae
Genera: Acer


The following species are discussed in this guide:

boxelder, A. negundo black maple, A. nigrum
red maple, A. rubrum silver maple, A. saccharinum
sugar maple, A. saccharum

Species boxelder, Acer negundo
Species Name Malay word for a similar tree. Boxelder refers to the resemblance of the leaves to those of elder, Sambucus spp., and the use of the wood in box making
Sites and Soils Boxelder is a tree of river bottoms and disturbed sites on heavy, wet soils. It is very successful in urban areas, especially on clay or heavy fill.
Ecology Boxelder is a quintessential bottomland tree: fast growing, short lived, a prolific seed producer, with weak wood. It is one of the most common bottomland trees throughout its range, growing in mixture with silver and red maples, American elm, American sycamore and sweetgum. Its range and abundance have increased dramatically since European settlement. Boxelder is very successful on disturbed urban sites where soil moisture is adequate, especially on heavy soils.
Life History Boxelder reproduces from seed, and is a very prolific, annual seed producer. The tree flowers in early spring and seeds are ripe in autumn. Seeds overwinter and germinate on exposed soil the following spring. Stump sprouts are common, root sprouts occasional. Exceptionally fast growing and short lived (ca 100 yrs). Boxelder is a medium-size tree, Champion 110'x5.3'; typical 40'x2'
Interactions VA mycorrhizal; wind pollinated;
Status Abundant, increasing since settlement.
RangeMap E. North America, scattered in Rocky Mts., Central Valley of California; naturalized N and W of original range. One of the largest ranges of any species.
Kentucky status Native, common
Kentucky range Entire state
Uses Boxelder is a low-value tree for commercial purposes; formerly planted as shelterbelt tree in midwest. Used for pulp and rough lumber, usually mixed with other bottomland species
Ornamental use No potential as an ornamental; should not be used, because of its aggressiveness as an urban weed.
Notes

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Species black maple, Acer nigrum
Species Name black.
Sites and Soils Black maple is found on a wide variety of sites, but performs best in rich bottoms on moderately well-drained soils, mostly West of the Appalachians.
Ecology Ecolgically as well as botanically, black maple closely resembles sugar maple, except that it is more commonly found on bottoms, often in mixture with red maple. It seems to be more drought tolerant than sugar maple. This may account for its more westerly distribution. Black maple is a tolerant, slow-growing, site-demanding species. Grows in mixed stands with other mesic site species. Often found in the understory on poorer sites, but rarely as a canopy tree.
Life History see sugar maple
Size
Interactions VA mycorrhizal; wind pollinated, insect pollinated.
Status Abundant, stable.
Range Midwest. Black maple is found mostly W of the Alleghanies, and becomes progressively more common further west. West of the Mississippi, black maple is the dominant maple species on uplands.
Kentucky status Abundant, stable
Kentucky range Entire state, becoming more abundant to the west.
Uses Not distinguished from sugar maple in utilization. see sugar maple
Ornamental use see sugar maple
Notes Some botanists treat black maple and sugar maple as a single species. They readily hybridize, and intermediate individuals are common. However, the morphological and ecological distinctions are sufficient to separate them. Black and sugar maple probably form a hybrid swarm similar to the oaks.

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Species Norway maple, Acer platanoides
Species Name Like platanus.
Sites and Soils
Ecology
Life History
Size
Interactions VA mycorrhizal; wind pollinated, insect pollinated.
Status Not native, naturalized in and around some urban areas, mostly in abandoned land.
Range Northern Europe
Kentucky status Not native, naturalized in and around Louisville, possibly in Northern Kentucky
Kentucky range
Uses Ornamental. Timber tree in Europe.
Ornamental use A widely used ornamental in North American cities. Considered more tolerant of soil compaction and drought than sugar maple. However, actual performance is often poor, especially in the South. Overused, and could be replaced with carefully selected cultivars of native maples.
Notes

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Species red maple, Acer rubrum
Species Name red
Sites and Soils Most common on bottomlands, but occurs on any site; the least site demanding species; may be outcompeted by more tolerant species on coves, lower slopes (the best sites). Red maple will grow on almost any soil.
Ecology Red maple grows on the widest variety of sites, and in the greatest range of conditions of any North American species. It is most abundant on bottom lands, though it does not follow the gallery forests as far west as elm or cottonwood. Red maple is strongly favored by disturbance, seeding and sprouting aggresively after fire, logging and abandonement of farmland. There has been an enormous increase in red maple's abundance since human activities began in the Eastern Deciduous Forest. Red maple is now the most abundant tree in the east, and is increasing. Trees which reproduce from stump sprouts after logging or fire frequently have butt rot.
Life History Red maple is the first tree to flower in the spring, sometimes even flowering in winter on warm days. A prolific spring seed producer, red maple reproduces from seeds, stump and root sprouts. Seeds germinate in spring without a dormant period, and early growth is rapid; some seeds may also enter the seed bank. Lifespan is 80-150 years. Establishment and early growth are best after disturbance. Intermediate to tolerant. Red maple is often classified as tolerant. However it exhibits significant intraspecific variation in tolerance.
Size Champion 179x5.8'; typical 60'x2'
Interactions VA mycorrhizal; wind pollinated; significant pests and pathogens are few; not a suitable food for gypsy moths.
Status abundant, increasing
Range Eastern Deciduous Forest, except Plains Extension
Kentucky status native, abundant
Kentucky range entire state
Uses Lumber is used for upholstered furniture framing, panelling, planing-mill products, boxes pallets; veneer for containers, plywood, core and cross-band use in panels, some figured veneer used for panel facing; pulpwood. Red maple is important because of its abundance.
Ornamental use Red maple is an excellent ornamental with many cultivars. It is not site demanding, suitable for most sites; trees should not be left to mature on small sites. In many communities, including most in Kentucky, red maple has been overused, and other species should be given more consideration.
Notes

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Species silver maple, Acer saccharinum
Species Name sweet
Sites and Soils Silver maple is restricted to bottomlands and stream banks in wet soils ranging in texture from gravel to clay. It does not climb slopes as do other bottomland species.
Ecology Silver maple is an abundant bottomland species, never found in dry soils. Silver maples can tolerate long periods of inundation, and seedlings will survive complete submergence provided the water is moving (and thus oxygenated). It occurs in mixed stands with boxelder, American elm, eastern cottonwood, American sycamore, red maple, river birch and willows; or occasionally in pure stands. Silver maple is very intolerant of competition, regenerating only after major disturbance, particularly after floods expose bare mineral soil.
Life History Silver maple bears abundant, wind- and insect-pollinated flowers in early spring. It is a prolific annual seed bearer, releasing seeds to the wind in early summer. Seeds germinate immediately on wet, bare soil. They will not survive in shade, and few seeds enter the seed bank. Silver maple also reproduces from stump and root sprouts, and from rooting of branches which break off. Growth is very rapid. Silver maple is a typical bottomland hardwood: fast growing, intolerant, weak wooded, short lived. Maximum size is typically about 80'x3' (Champion 125'x7.3'). Trees rarely live for more than 150 years. Silver maple has exceptionally weak wood, and is prone to breaking up in wind, or suffering damage of the stem during flooding. This allows decay fungi to become established, and trees gradually break up.
Size
Interactions VA mycorrhizal; wind- and insect-pollinated.
Status Abundant; stable, though much habitat has been converted to farm land.
Range Eastern Deciduous Forest except southern Atlantic Coastal Plain and much of the Gulf Coastal Plain.
Kentucky status Abundant; stable
Kentucky range Entire state; in Cumberland Plateau, it is only found along major rivers.
Uses Important source of rough lumber, pulp.
Ornamental use Formerly an important ornamental because of its rapid growth, silver maple is now banned in many communities. Silver maples become quite large and break up easily in stormy weather, presenting a hazard in cities. Silver maple roots will penetrate septic systems, sewer pipes and foundations. Use of this species should be discouraged.
Notes

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Species sugar maple, Acer saccharum
Species Name sweet
Sites and Soils Sugar maple is site demanding, growing best in coves, lower slopes, mesic woods. Sugar maple can be found on poorer sites, including dry uplands or thin, rocky soils, but does not thrive.
Ecology Sugar maple is a tolerant, slow-growing, site-demanding species. Mature trees are indicators of rich sites. Grows in mixed stands (occ. pure stands in Northern Hardwood forests) with other mesic site species. Often found in the understory on poorer sites, but rarely as a canopy tree.
Life History Sugar maple bears wind- and insect-pollinated flowers in spring, and seeds are dispersed in fall of the same year. Seeds are mod. abundant every year, with peak years at 2-5 year intervals. Seeds germinate in spring after overwintering, or form a seed bank and germinate in subsequent years. Germination occurs on moist mineral soil or in the litter layer. Early growth is slow, and depends on light levels. Sugar maple is a fairly slow growing species, and among the most tolerant trees. Trees can live 300-500 years, possibly longer.
Size Champion 91'x7'; typical 60-80'x2'
Interactions VA mycorrhizal; wind pollinated, insect pollinated.
Status Abundant, populations stable. Some evidence of increase in rate of decline and dieback See notes.
Range Northern 2/3 of Eastern Deciduous Forest, Tennessee to Quebec, W. to Minn, Neb.; replaced in deep south by A. floridanum.
Kentucky status native, abundant
Kentucky range entire state
Uses A very important timber tree, for its hard, often figured, wood; furniture, cabinets, veneer, musical instruments; syrup; ornamental
Ornamental use Highly recommended on very good to excellent sites; best in parks, large yards where soil compaction is not a concern; not a good street tree; susceptible to stem and root injury, girdling roots; very sensitive to compaction; susceptible to air pollution; autumn foliage very showy; many cultivars available;
Notes Maple declines from unknown causes have been observed in the NE US and S. Canada in recent years. Acid precipitation and air pollution may play a role, but there is little direct evidence to support this. Increased nitrogen inputs may also destabilize sugar maple forests. Poor management, including wounding of young trees during harvesting operations, may be more important. Drought is also a major factor in maple decline. Climate change is a major concern for this species.

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