|Bigtooth maple, Wasatch Mountains, Utah|
Acer grandidentatum (bigtooth maple) is a species of maple native to interior western North America, occurring in scattered populations from western Montana in the United States south to Coahuila in northern Mexico. It is closely related to Acer saccharum (sugar maple), and is treated as a subspecies of it by some botanists, as Acer saccharum subsp. grandidentatum (Nutt.) Desmarais.
It is a small to medium-sized deciduous tree growing to 10–15 m tall and a trunk of 20–35 cm diameter. The bark is dark brown to gray, with narrow fissures and flat ridges creating plate-like scales; it is thin and easily damaged. The leaves are opposite, simple, 6–12 cm long and broad, with three to five deep, bluntly-pointed lobes, three of the lobes large and two small ones (not always present) at the leaf base; the three major lobes each have 3–5 small subsidiary lobules. The leaves turn golden yellow to red in fall (this trait is less reliable in warmer areas).
The flowers appear with the leaves in mid spring; they are produced in corymbs of 5–15 together, each flower yellow-green, about 4–5 mm diameter, with no petals. The fruit is a paired samara (two winged seeds joined at the base), green to reddish-pink in color, maturing brown in early fall; each seed is globose, 7–10 mm diameter, with a single wing 2–3 cm long.
It commonly grows in limestone soils but can adapt to a wide range of well-drained soils, from sand to clays to even white limestone areas. It prefers valleys, canyons, and the banks of mountain streams, primarily at higher elevations such as the mountain ranges of Utah, Arizona, and New Mexico and some adjacent states. However, bigtooth maple can survive at lower elevations in sheltered canyons, for example in the mountains of west Texas and the Edwards Plateau in Texas (where a population is protected in the Lost Maples State Natural Area). Although continental climates prevail over all of its natural range, it grows well in the maritime climate of Vancouver. It is slow growing when young, and does not have many pests.
It is occasionally planted as an ornamental tree, valued for its drought tolerance and ability to grow in rocky landscapes.
Other vernacular names occasionally used include lost maple, Sabinal maple, western sugar maple, Uvalde big tooth maple, canyon maple, southwestern big tooth maple, plateau big tooth maple, limerock maple, Wasatch maple and Rocky Mountain sugar maple.
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