Aceraceae: Acer glabrum
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Family Name
Aceraceae (Sapindaceae)
Common Name
Rocky Mountain maple
Description
Acer glabrum is a deciduous shrub or small tree typically growing 3 to 9 meters tall, characterized by smooth to slightly rough bark. Leaves are opposite, simple, and palmately lobed with 3 to 5 lobes, measuring 5 to 12 centimeters long and 6 to 14 centimeters wide, with petioles about 3 to 9 centimeters long. Leaves are glabrous or sparsely hairy. Flowering occurs from April to June, with flowers borne in small corymbs. Each flower is about 5 to 8 millimeters in diameter, having five greenish-yellow petals approximately 2 to 3 millimeters long and 1 to 1.5 millimeters wide, and five green sepals roughly 1.5 to 3 millimeters long and 0.5 to 1.5 millimeters wide. There are eight stamens inserted around the ovary, with filaments about 3 to 5 millimeters long and small anthers. The pistil consists of two fused carpels forming a superior ovary, with a short style and a bifid stigma. The fruit is a paired samara with wings spreading at nearly 180 degrees, each samara about 15 to 25 millimeters long and 5 to 7 millimeters wide, maturing from late summer to early fall. Rocky Mountain maple is native to western North America and is found in South Dakota primarily in the Black Hills, growing in montane forests and along stream banks.
Horticulture Notes
Seed collection: Late summer to early fall as samaras mature.
Germination: Seeds require cold stratification for best germination rates.
Propagation: By seed and sometimes by layering.
Soils: Prefers moist, well-drained soils, often found in rocky or gravelly substrates.
Light: Full sun to partial shade.
Water: Prefers moderate moisture; tolerates some drought once established.
Additional Notes
The wood is valued for carving and craftwork, while the tree provides important shade and habitat for wildlife. It is used ornamentally in native plant landscaping and restoration projects.