Purpletop

Tridens flavus

Weed Description
A perennial with short, thick rhizomes that is most noticeable from August through October when these plants reach 4 or 5 feet in height and produce dark purple panicles. Purpletop is primarily a weed of hay fields, pastures, abandoned fields, and roadsides that is found from New Hampshire south to Florida.

Leaves
Leaves are somewhat flattened and appear folded in the sheath and have a relatively prominent white midvein. Leaves are 8 to 17 mm wide, usually hairy except near the bases, lacking auricles, and with a ligule that is a fringe of hairs less than 1 mm in length.

Stems
Sheaths are round and usually hairy only near the top. Plants may reach 4 to 5 feet in height when mature.

Flowers
The seedhead is an open panicle that is dark purple in color. Individual spikelets are 6 to 8 mm long, 1 to 2 mm wide, and purple in color.

Roots
Short, thick rhizomes occur along with a fibrous root system.

Identifying Characteristics
A grass with relatively wide leaves that have a very small ligule that is a fringe of hairs. Additionally, the short, thick rhizomes and purple seedhead are characteristics that help in the identification of this weed.

Office of Programs

University of Missouri

Purpletop

Tridens flavus