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| ## rocky mountain maple {#rocky-mountain-maple .Title-Header}         |
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| *Acer glabrum* Torr.                                                  |
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| Plant Symbol = ACGL                                                   |
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## *Contributed By: USDA NRCS National Plant Data Center & the Biota of North America Program*

## Alternate common names

Mountain maple, Douglas maple, Douglas Rocky Mountain maple, three leaf
Rocky Mountain maple, rose-fruit Rocky Mountain maple, Sierra maple,
California mountain maple, New Mexico maple, box maple, rock maple,
dwarf maple,

## Uses

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.

## Status![](media/image2.jpeg){width="2.6944444444444446in" height="1.7965277777777777in"}

Please consult the PLANTS Web site and your State Department of Natural
Resources for this plant's current status, such as, state noxious status
and wetland indicator values.

## Description 

*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 distribution.

*Variation within the species*: Numerous varieties of Rocky Mountain
maple have been described primarily on the basis of variation in
stature, twig color, leaf lobing and size, and fruit shape. The
following are currently recognized.

Var. *diffusum* (Greene) Smiley

Var. *douglasii* (Hook.) Dippel

Var. *glabrum*

Var. *greenei* Keller

> Var. *neomexicanum* (Greene) Kearney and Peebles

Var. *torreyi* (Greene) Smiley

*Distribution:* 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).

## Establishment

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.

## Management

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--5^o^C, but
viability may be no more than 1-3 years. Warm stratify at 20--35.5^o^C
for 180 days and then moist chill at 3--5^o^C for 180 days; or moist
chill for 3--6 months at 3--5^o^C. 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).

## Cultivars, Improved and Selected Materials (and area of origin)

Rocky Mountain maple is available a nurseries within its range.

## References

Olson, D.F., Jr. & W.J. Gabriel 1974. *Acer* L. In: C.S. Schopmeyer
(techn. coord.). *Seeds of woody plants in the United States*. Agric.
Handb. 450. USDA, Forest Service, Washington, DC.

Shaw, N. 1984. *Producing bareroot seedlings of native shrubs*. In: P.M.
Murphy (compiler). *The challenge of producing native plants for the
Intermountain area: Proceedings, Intermountain Nurseryman\'s Association
conference*; Las Vegas, 1983. Gen. Tech. Rep. INT-168. USDA, Forest
Service, Intermountain Forest and Range Experiment Station, Ogden, UT.

Uchytil, R. J. 1989. *Acer glabrum*. IN: W.C. Fischer (compiler). *The
fire effects information system* \[Data base\]. USDA Forest Service,
Intermountain Research Station, Intermountain Fire Sciences Laboratory,
Missoula, Montana. \<http://www.fs.fed.us/database/feis/\>

Vories, K.C. 1981. *Growing Colorado plants from seed: A state of the
art. Volume I. Shrubs*. Gen. Tech. Rep. INT-103. USDA, Forest Service,
Intermountain Forest and Range Experiment Station, Ogden, Utah.

Wenger, K.F. (ed.) 1984. *Forestry handbook* (ed. 2). John Wiley & Sons,
New York, New York.

## Prepared By

*Guy Nesom*, BONAP, North Carolina Botanical Garden, University of North
Carolina, Chapel Hill, North Carolina

## Species Coordinator

*Lincoln Moore*, USDA, NRCS, National Plant Data Center, Baton Rouge,
Louisiana

Edited: 13nov00jsp; 07feb03ahv; 24may06jsp

For more information about this and other plants, please contact your
local NRCS field office or Conservation District, and visit the PLANTS
Web site\<[http://plants.usda.gov](http://plants.usda.gov/)\> or the
Plant Materials Program Web site
\<[http://Plant-Materials.nrcs.usda.gov](http://Plant-Materials.nrcs.usda.gov/)\>

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