Rocky Mountain Maple (Glabrum)

The Rocky Mountain Maple (Glabrum) is generally described as a perennial tree or shrub. This is native to the U.S. (United States) has its most active growth period in the spring and summer . The greatest bloom is usually observed in the late spring, with fruit and seed production starting in the summer and continuing until fall. Leaves are not retained year to year. The Rocky Mountain Maple (Glabrum) has a moderate life span relative to most other plant species and a rapid growth rate. At maturity, the typical Rocky Mountain Maple (Glabrum) will reach up to 30 feet high, with a maximum height at 20 years of 15 feet.

The Rocky Mountain Maple (Glabrum) is easily found in nurseries, garden stores and other plant dealers and distributors. It can be propagated by bare root, container, cuttings, seed. It has a slow ability to spread through seed production and the seedlings have low vigor. Note that cold stratification is not required for seed germination and the plant cannot survive exposure to temperatures below -43°F. has medium tolerance to drought and restricted water conditions.

Uses of : Landscaping, Medicinal, Culinary, etc.

Rocky Mountain maple is planted to a limited extent to improve wildlife habitat, to stabilize slopes, and to provide low-maintenance landscaping. The striking red bark and contrasting light green leaves, turning red in the fall, make it a desirable ornamental shrub. Rocky Mountain maple is a highly valued big game browse species. Moose, elk, mule deer, and white-tailed deer to varying degrees throughout the year eat its leaves and twigs, but it is especially important as a winter food source. Post-wildfire brush fields, with Rocky Mountain maple as an important component, are prime winter range and provide both cover and food for moose, elk, and deer. The species also provides considerable cover and nesting habitat for many game birds, songbirds, and small mammals, especially where the maples grow more densely in open habitats. In commercial timber operations, shrub fields of Rocky Mountain maple often interfere with seedling establishment and early growth of conifers, and the maple is removed.

The easily bendable stems were used by various American Indian tribes to make drying racks, drum hoops, snowshoe frames, spears, pegs, toys, and masks. The fibrous bark was woven into mats and rope. A bark decoction was used as a poison antidote.

General Characteristics

General: Maple Family (Aceraceae): This is a native shrub 1.5-2 m tall or trees 6-10(-12) m tall, variable in form, with short trunk(s) and slender, upright branches, hairless, with slender, reddish-brown shoots and thin; bark smooth, gray or brown. The leaves are deciduous, opposite, 4-12 cm long and wide, sometimes smaller, sometimes divided into three lanceolate leaflets but usually palmately 3(-5)-lobed and veined, the lobes ovate with narrowly acute sinuses and double-toothed edges, with a reddish petiole, shiny dark green above, paler or whitish beneath, turning pale yellow to yellowish-orange or crimson in fall. The flowers are greenish-yellow, with petals usually present, in short, branched terminal or axillary flat-topped clusters 2.5-5 cm long, on drooping stalks. The male and female flowers are usually on separate plants (the species essentially dioecious) or on the same plant (the species technically polygamo-dioecious). The fruits are winged nutlets (samaras) 2.5 cm long, often reddish tinted at maturity, in a long-stalked, wide-spreading pair. The common name is derived from the predominantly Rocky Mountain

Required Growing Conditions

Rocky Mountain maple is broadly distributed in the western U.S., from southeastern Alaska, British Columbia, and southwestern Alberta, south from western Washington to southern California and east to southern New Mexico, northwestern Nebraska, and Montana. For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site.

Adaptation Moist but well-drained seepage sites, mostly in rocky areas, along streambanks, moist slopes, canyons, and ravines, sometimes dry ridges, at low to middle elevations and moist sites in high mountains, 900-3300 meters. Rocky Mountain maple is a long-lived, shade-tolerant seral species that often persists in the understory of late seral or climax coniferous stands, usually Douglas fir, grand fir, subalpine fir, white fir, or Engelmann spruce. Because of its sprouting ability, it often gains dominance in seral shrub communities after conifer overstories are eliminated or reduced by wildfire or logging.

This species flowers in April-June(-July) and fruits in August(-September and October).

Cultivation and Care

Rocky Mountain maple begins to produce seed probably before 10 years of age, but “resprouts” may produce seed by 5 years after a fire. Seed is produced annually but large seed crops may not be produced every year. The seeds require approximately 6 months of chilling to break embryo dormancy, usually supplied under natural conditions for spring germination. They quickly lose viability after the first year in storage as well as under natural conditions. Germination and early establishment occur best in partial shade, but rates of germination and establishment are generally low.

Rocky Mountain maple produces numerous root crown sprouts following disturbances from fire or logging, but it does not appear to spread from root suckers or rhizomes. It is difficult to grow from cuttings.

General Upkeep and Control

Most fires top-kill Rocky Mountain maple but root crown sprouts allow it to persist or increase in postfire communities. Hot fires may damage root crowns. Rocky Mountain maple in northern Idaho sprouts 4-8 weeks after prescribed burns in spring (when plants are still in winter dormancy) and sprouts the following spring after fall burning. Summer prescribed fires are helpful to an associated species redstem ceanothus (Ceanothus sanguineus), which requires high temperatures to crack seedcoats prior to germination.

Rocky Mountain maple is best established by transplanting 2-year-old or older stock. To produce seedlings for transplanting, seed may be sown directly in the field or in nursery beds. Unstratified seed should be planted in the fall for best results; stratified seed is planted in the spring. Seeds should be stored in sealed containers at 1.6–5oC, but viability may be no more than 1-3 years. Warm stratify at 20–35.5oC for 180 days and then moist chill at 3–5oC for 180 days; or moist chill for 3–6 months at 3–5oC. Planting depth is 0.6–2.5 centimeters. Guidelines for seed storage, treatment, growing seedling transplants, and planting are summarized in Olson (1974), Shaw (1984), and Wenger (1984).

Plant Basics
Growth Rate Rapid
General Type Tree, Shrub
Growth Period Spring, Summer
Growth Duration Perennial
Lifespan Moderate
Plant Nativity Native to U.S.
Commercial Availability Routinely Available
Physical Characteristics
Bloom Period Late Spring
Displays Fall Colors Yes
Shape/Growth Form Multiple Stem
Drought Tolerance Medium
Shade Tolerance Intermediate
Height When Mature 30
Vegetative Spread Slow
Flower Color Green
Flower Conspicuousness No
Fruit/Seed Abundance High
Fruit/Seed Seasonality Summer Fall
Seed Spread Rate Slow
Gardening Characteristics
Propagations (Ways to Grow) Bare Root, Container, Cuttings, Seed
Moisture Requirements Low
Cold Stratification Required Yes
Minimum Temperature -43
Soil Depth for Roots 24
Toxic to Nearby Plants No
Toxic to Livestock No
After-Harvest Resprout Ability Yes
Responds to Coppicing No
Growth Requirements
pH Range 5.8–7.5 pH
Precipitation Range 12–12 inches/yr
Planting Density 300–1200 indiv./acre
Soil Textures Coarse, Medium
Soil Depth for Roots 24
Minimum Frost-Free Days 180 day(s)
Salinity Tolerance None
CaCO3 Tolerance Medium
Sustainability & Use
Leaf Retention No
Palatability High
Fire Resistant No

Source: USDA, NRCS, PLANTS Database,
National Plant Data Center, Baton Rouge, LA 70874-4490 USA