Rocky Mountain Maple, Rock Maple, Douglas Maple, Dwarf Maple                A-ser GLAH-brum

• Broadleaf deciduous small tree, to 30 ft (10 m) tall, often multi-stemmed, upright.  Leaves opposite, simple, 7-14 cm long, about as wide, 3-5 lobes (occasionally divided into 3 leaflets, more common in moist areas), coarsely double toothed, green above, blue-green below; petiole long (3-12 cm), slender, often red.   Fall color yellow.  Flowers 5 mm across, yellowish green, with 5 petals.  Fruit wings 18-22 mm long, nearly parallel.
• Sun to part shade.
• Hardy to USDA Zone 4    Native range from southeastern Alaska south to northern California, east to British Columbia, Alberta, Idaho and Montana and south to Wyoming, Utah, Colorado, Arizona to New Mexico.  Found along streams and other moist sites.
• Some six varieties or subspecies are often recognized:
  • Acer glabrum var. diffusum  [Rocky Mountain Maple]  -  small leaves and white twigs; eastern California, Nevada, Utah.
  • Acer glabrum var. douglasii  [Douglas Maple]  -  3-5 lobed, swallow sinuses, red twigs; southern Alaska, British Columbia, Alberta, Montana, Idaho, Washington and Oregon.
  • Acer glabrum var. glabrum  [Rocky Mountain Maple]  -  larger form, Rocky Mountains, Idaho, Wyoming to western Nebraska, Colorado, Utah, to Arizona.
  • Acer glabrum var. greenei  [Greene's Maple]  -  very small leaves, samaras with overlapping wings, southern Sierra Nevada.  [Douglas Justice (Univ. British Columbia, MSc, 1995) concluded from field and herbarium studies that A. g. var. greenei did not represent a valid taxa.]  (This work is available on line; search, douglas justice acer glabrum.)
  • Acer glabrum var. neomexicanum  [New Mexico Maple]  -  leaves 5-10 cm, 3-parted or nearly so; southern Colorado, New Mexico, southern Utah, and southeastern Arizona.
  • Acer glabrum var. torreyi  [Sierra Maple]  -  5-lobed leaves and samaras whose wings are spread at about 45°; southern Oregon, northern California and Nevada.
• glabrum: without hairs.
• Oregon State Univ. campus: south (east) Peavy Hall, north of Dryden Hall