These are hairy, coarse-looking plants, often with several to many stems arising from a crown. The corolla is reddish to maroon, and the fruits are orange to red. A third species, Triosteum angustifolium L. occurs as close as the Lake Erie Islands in Ontario, and might be found in the Lake Erie region of Michigan. It is a more slender and narrow-leaved plant, with sepals strongly ciliate on the margins, rather than with pubescence on the margins similar to that of the surface, as in our two species.

This is one of the genera of eastern North America that reappears in temperate eastern Asia, where there are three additional species. 

1. Principal mid-cauline leaves tapered to narrow base (but upper leaves often narrowly connate); stem pubescence often chiefly of long (ca. 1-2 mm) eglandular hairs (usually with some short eglandular or gland-tipped hairs besides); style equaling or slightly shorter than the corolla (rarely exserted).

T. aurantiacum

1. Principal mid-cauline leaves both ca. 3-5 cm broad at the base and connate (upper leaves merely tapered basally); stem pubescence all or mostly of ± dense, short (0.5 mm or less), gland-tipped hairs; style exserted beyond the corolla.

T. perfoliatum