SAPINDACEAE - - Soapberry Family

Acer rubrum L. var. trilobum Torrey & A. Gray ex K. Koch — Trident Maple or Carolina Red Maple

Trident Maple or Carolina Red Maple (Acer rubrum var. trilobum) is, of course, only a variety of Eastern Red Maple (Acer rubrum var. rubrum) and is very similar to that taxon in many characters. Trident Maple is separated from Eastern Red Maple primarily by leaf characteristics and to some degree habitat. These attributes will be discussed in the following two paragraphs. Also, a close examination of the leaf photos of each species will be very helpful.

Separating Characteristics

As mentioned in the introductory paragraph the leaves are the main separating character. The leaves of this species are usually 3-lobed rather than 5-lobed as with var. rubrum and the base of the leaves are more rounded. And, because of these characteristics, the leaves have shorter and more rounded teeth. It is also reported that Trident Maple is more likely to have yellow fall color, while var. rubrum tends to have red fall foliage.

Habitat

The other possible separating factor is habitat. Here in northwest Georgia, var. trilobum is a strictly flatwoods, lowland species, not found on the mountains and ridges. These higher elevations is usually where you find var. rubrum although you can't completely rule out the possibility of finding it in lowland situations also. The flatwoods habitat in northwest Georgia, that Carolina Red Maple prefers, is calcareous, not acidic as reported by other resources. The mountain and ridge habitat preferred by var. rubrum is acidic.

Native Range

The reported range of Carolina red maple from USDA's National Plants Database is almost the same as var. rubrum except that var. trilobum seems to be missing from Michigan, Wisconsin, Minnesota and Iowa. Weakley in his "Flora of the Southern and Mid-Atlantic States" states that Carolina red maple is "Primarily a Southeastern Coastal Plain variety, the range of var. trilobum is unclear, possibly extending well inland and northward." He is correct and I will add that it definitely does extend inland in the great river valleys that extend into northwest Georgia, such as the Coosa, Etowah and Oostanaula rivers.

The native range of Acer rubrum var. trilobum (Carolina Red Maple)

USDA, NRCS. 2018. The PLANTS Database (http://plants.usda.gov, Various Dates). National Plant Data Team, Greensboro, NC 27401-4901 USA.