Acer glabrum (ay’-sir gale’-brum)
Family: Sapindaceae, Soapberry

Key Steps

• 1a – Opposite leaf arrangement on stem — go to 2
  • 2a – Leaf simple — go to 3
    • 3a – Leaves are lobed — go to 4
      • 4b – No milky sap — go to 5
        • 5b – Margins of lobes are toothed — go to 7
          • 7a – Three to five lobes — go to 8
            • 8b – Lobes fairly similar in size. Base of middle lobe is wide. Sinuses are V-shaped and toothed — go to 10
              • 10b – Native tree; can be multi-stemmed. Leaves less than 3 inches wide — Rocky Mountain Maple

Description

Leaf: Three large main lobes, sometimes 2 smaller lower lobes. Middle lobe sometimes wide at base, sometime so narrow at base it divides and become a compound leaf. Margins of lobes coarsely serrate. Petiole smooth, thick, red, 1-6 inches long.

Bud: Red, pointed, 1/8 to 1/4 inch long.

Leaf Scar: Crescent-shaped.

Stem: Slender, smooth. Reddish or pale green when young. Gray when older.

Bark: Tight, thin, smooth, dark red-brown to gray.

Flower: Yellow-green in small clusters in early spring.

Fruit: Samara, two wings, each wing one inch long, reddish, hanging in clusters.

Habit: Can be multi-stemmed, small, clump-forming. Colorado native in foothills, montane, and streambanks.

Culture: Shade tolerant. Moderate moisture requirement.

Resources

• Identifying Broadleaf Flowering Trees and Shrubs, CMG GardenNotes #173
• List of trees in this key
• Glossary of Terms
• Front Range Tree Recommendation List
• Online CSU Extension publications on Tree and Shrub Selection