Erect, unbranched perennial plants topped with open clusters of bright red flowers. Flowers with 5 petals, each entire or finely toothed at the tip but rarely notched and never lobed; bright red; with a pair of small appendages on the upper surface at the base of the expanded portion. Blooms May-October. Stems with short, stiff, down-pointed hairs at the base, and stalked glands toward the top. Basal leaves usually absent by flowering time. Stem leaves opposite, sessile, ovate to lanceolate, tapered, rounded or heart-shaped at the base, the surfaces more or less roughened and hairy or smooth.