Scientific name: Tridens flavus
Common name: Purpletop
Family: Poaceae
Plant type: Grass

Purpletop (Tridens flavus) is aptly named for its striking reddish purple seedheads, bright splashes of color to catch the eye. The warm season bunchgrass grows in clusters of erect culms (stems) that typically grow 3-6’ high. Its leaf blades are flat, narrow, alternate, keeled (having a central rib), and about 10-27” long. The culms and leaves are medium green in color, turning brown in autumn. After the foliage matures, a seedhead appears atop each culm in the form of an open, spreading panicle. Panicles are 8-14” long, pyramidal, and drooping, comprised of widely spaced, delicate branchlets (either single or in whorls of 2-3) distributed along a fine rachis (central stalk). Reddish-purple spikelets (grain-like flowers) attach to the branchlets via fine pedicels. The seedheads are oily, which prompts the species second common name: grease grass. The bloom time for purpletop is August-November; however, individual plants may only keep their colorful tops for a few weeks. After they are pollinated, they turn brown. Purpletop tolerates various soil types and is resistant to many herbicides. It makes a picturesque statement when planted en masse. Smaller plantings pair well with yellow wildflowers, such as goldenrods. It is not aggressive, though, and can be outcompeted if planted among strong spreaders. Purpletop serves as a larval host for moth species, including several of the skippers, and its seedheads provide an autumn feast for birds and mammals.

Credits: Text and photos by Valerie Boss.


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