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Acer glabrum

Acer glabrum (Red Maple, Rocky Mountain Maple)
Sapindaceae (Soapberry Family)
formerly Aceraceae (Maple Family)

Foothills, montane. Woodlands. Spring.
Taylor Creek Trail, June 2, 2004.

Acer glabrum is common throughout the Four Corners states and the rest of the West.  It typically grows to only 20 or 30 feet tall in dense clumps of small trunks in moist woods.  It has distinctive, handsome, serrated, and deeply cut  leaves which often have red galls. (See photograph below.)  Leaves turn yellows and reds in the fall.

Linnaeus named this genus in 1753.  "Acer" is the ancient Latin name for Maples.  Edwin Greene collected the first specimen of this species in Colorado in 1820 and John Torrey named it in 1827.  "Glabrum" is from the Latin for "smooth".

Acer glabrum

Acer glabrum (Red Maple, Rocky Mountain Maple)
Sapindaceae (Soapberry Family)
formerly Aceraceae (Maple Family)

Foothills, montane. Woodlands. Spring.
Lower Calico Trail, June 7, 2013.

Acer glabrum flowers open with the leaves in loose terminal clusters. Flowers are unisexual but do have reduced stamens with functional pistils or reduced pistils with functional stamens.

Acer glabrum

Acer glabrum

Acer glabrum (Red Maple, Rocky Mountain Maple)
Sapindaceae (Soapberry Family)

formerly Aceraceae (Maple Family)

Foothills, montane. Woodlands. Spring.
Taylor Creek Trail, June 2, 2004 and Vallecito Creek Trail, September 12, 2011.

 
Leaves are commonly cut almost to the mid-rib into three sections.  Occasionally the leaves are in three distinct sections.

 

Acer glabrum

Acer glabrum

Acer glabrum

Acer glabrum (Red Maple, Rocky Mountain Maple)
Sapindaceae (Soapberry Family)
formerly Aceraceae (Maple Family)

Foothills, montane. Woodlands. Spring.
Lower Calico Trail, June 11, 2011 and June 16, 2004.

The red swellings are quite common erinea, abnormal felty growth of hairs on the leaves, caused, in the case of Acer glabrum, by the Eriophid Mite, Eriophyes calaceris.

Acer grandidentatum

Acer grandidentatum (Big Tooth Maple, Canyon Maple)
Sapindaceae (Soapberry Family)
formerly Aceraceae (Maple Family)

Foothills, montane. Woodlands. Spring.
Robertson Pasture Trail, Utah, May 31, 2006.

Acer grandidentatum occurs commonly in Utah, in scattered areas in Arizona and New Mexico, and rarely in two western counties of Colorado.  Its leaves are usually a bit larger than those of Acer glabrum (see above) but are not serrated.  Acer grandidentatum grows about the same height as A. glabrum and it, too, frequently has multiple, small main trunks but it can have a robust trunk, as in the left photo.  It commonly forms thickets with Quercus gambelii (the two dark trunks at the upper right of the photograph).  Acer grandidentatum is a close relative of the Sugar Maple.

Thomas Nuttall, acclaimed 19th century Professor, explorer, and taxonomist, collected the first specimen of this tree in the Northern Rockies (probably in the mid-1830s).  He named it in 1838.

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Range map for Acer glabrum

Range map for Acer grandidentatum