Rocky Maple Acer glabrum
Other Common Name(s):
Previously known as:
- Acer glabrum subsp. typicum
- Acer glabrum var. typicum
- Phonetic Spelling
- AY-ser GLAH-brum
- Description
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Rocky Mountain maple is a deciduous shrub or small shade tree in the maple family (Sapindaceae) and is native to western North America from Alaska south to California and west to Nebraska and south to New Mexico. The specific epithet means smooth, without hair, referring to its smooth stems and leaves. The species is named after David Douglas, a Scottish botanist who in addition to this tree, is also known for the Douglas fir.
This tree will grow 12-30 feet in height and spread 10 to 20 feet wide. It usually has a multi-trunk habit and a shrub-like growth and a narrow crown in more open areas. It can be tall and spindly in closer stands of trees. Can withstand sandy, loamy, and heavy clay acidic soils, prefers well-drained soil and needs lots of organic matter. It performs best in semi-shade to shade. Plant in a location sheltered from strong winds, frost, and afternoon sun. This is a relatively low-maintenance tree, and should only be pruned in summer after the leaves have fully developed, as it may 'bleed' sap if pruned in late winter or early spring.
There are three varieties depending on what region they are growing in. They are listed below.
It is primarily grown for its ornamental red fruit in the late summer and fall and its interesting red twigs that stand out, particularly in the winter. The fall color is knock-out yellow-to-red.
Works well for erosion control, in a woodland garden and as an understory tree. Best grown in its native habitat and would not be appropriate for the southeast.
Insects, Diseases, and Other Plant Problems: No significant insect or disease problems. In alkaline soils, it can develop manganese chlorosis. Watch for aphids, leafhoppers, borers, scale, and caterpillars. Also note that verticillium wilt attacks the vascular system and can be fatal. Canker, fungal leaf spot, and root rots may also occur. Wind and ice may break some branches.
The Clemson Cooperative Extension Home and Garden Information Center has a factsheet on common maple diseases and insect pests.
- See this plant in the following landscape:
- Cultivars / Varieties:
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- var. diffusum
Found in dry mountain slopes - var. douglasii
Found coastal southeast Alaska and British Columbia, to southern Oregon; east to Idaho and Montana. - var. glabrum
Variety found in non-coastal regions of the west.
- var. diffusum
- var. diffusum, var. douglasii, var. glabrum
- Tags:
- Cultivars / Varieties:
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- var. diffusum
Found in dry mountain slopes - var. douglasii
Found coastal southeast Alaska and British Columbia, to southern Oregon; east to Idaho and Montana. - var. glabrum
Variety found in non-coastal regions of the west.
- var. diffusum
- var. diffusum, var. douglasii, var. glabrum
- Tags:
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Attributes:
- Genus:
- Acer
- Species:
- glabrum
- Family:
- Sapindaceae
- Life Cycle:
- Woody
- Recommended Propagation Strategy:
- Seed
- Country Or Region Of Origin:
- Western North America
- Distribution:
- Alaska, Alberta, Arizona, British Columbia, California, Colorado, Idaho, Mexico Northeast, Montana, Nebraska, Nevada, New Mexico, Oregon, South Dakota, Utah, Washington, Wyoming, Yukon
- Wildlife Value:
- Members of the genus Acer support Imperial Moth (Eacles imperialis) larvae which have one brood per season and appear from April-October in the south. Adult Imperial Moths do not feed. Food and shelter to wildlife
- Play Value:
- Attracts Pollinators
- Pieces Used in Games
- Wildlife Cover/Habitat
- Wildlife Food Source
- Wildlife Nesting
- Particularly Resistant To (Insects/Diseases/Other Problems):
- erosion
- Dimensions:
- Height: 12 ft. 0 in. - 30 ft. 0 in.
- Width: 10 ft. 0 in. - 20 ft. 0 in.
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Whole Plant Traits:
- Plant Type:
- Shrub
- Tree
- Woody Plant Leaf Characteristics:
- Deciduous
- Habit/Form:
- Erect
- Multi-trunked
- Rounded
- Spreading
- Growth Rate:
- Rapid
- Maintenance:
- Low
- Texture:
- Medium
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Cultural Conditions:
- Light:
- Dappled Sunlight (Shade through upper canopy all day)
- Full sun (6 or more hours of direct sunlight a day)
- Partial Shade (Direct sunlight only part of the day, 2-6 hours)
- Soil Texture:
- Clay
- High Organic Matter
- Loam (Silt)
- Sand
- Soil pH:
- Acid (<6.0)
- Soil Drainage:
- Good Drainage
- Moist
- Occasionally Dry
- Very Dry
- USDA Plant Hardiness Zone:
- 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b
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Fruit:
- Fruit Color:
- Brown/Copper
- Green
- Pink
- Red/Burgundy
- Display/Harvest Time:
- Fall
- Summer
- Fruit Type:
- Samara
- Fruit Length:
- < 1 inch
- Fruit Description:
- Red winged samaras. This plant has green, insignificant flowers in April, which are pollinated by insects and followed by showy red winged samaras in late summer. Plant is dioecious.
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Flowers:
- Flower Color:
- Green
- Flower Inflorescence:
- Cyme
- Insignificant
- Flower Value To Gardener:
- Fragrant
- Flower Bloom Time:
- Spring
- Flower Size:
- < 1 inch
- Flower Description:
- Green, insignificant flowers in April in terminal drooping cymes. The flowers are dioecious (individual flowers are either male or female, but only one sex is to be found on any one plant so both male and female plants must be grown for pollination to occur.
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Leaves:
- Woody Plant Leaf Characteristics:
- Deciduous
- Leaf Color:
- Gold/Yellow
- Green
- Pink
- Red/Burgundy
- Deciduous Leaf Fall Color:
- Gold/Yellow
- Red/Burgundy
- Leaf Margin:
- Lobed
- Hairs Present:
- No
- Leaf Width:
- 1-3 inches
- Leaf Description:
- Lobed leaves green most of the year turn yellow to brick red in the fall.
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Bark:
- Bark Color:
- Dark Brown
- Dark Gray
- Light Brown
- Light Gray
- Surface/Attachment:
- Fissured
- Smooth
- Bark Description:
- Smooth, brownish gray bark becomes fissured with age
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Stem:
- Stem Color:
- Red/Burgundy
- Stem Is Aromatic:
- No
- Stem Surface:
- Smooth (glabrous)
- Stem Description:
- The stems are smooth and red in winter.
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Landscape:
- Landscape Location:
- Slope/Bank
- Woodland
- Landscape Theme:
- Butterfly Garden
- Children's Garden
- Nighttime Garden
- Pollinator Garden
- Shade Garden
- Winter Garden
- Design Feature:
- Shade Tree
- Understory Tree
- Attracts:
- Butterflies
- Moths
- Pollinators
- Small Mammals
- Songbirds
- Resistance To Challenges:
- Diseases
- Erosion
- Insect Pests
