Scientific Name: Tridens flavus

Common Name: purpletop

Habit: 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

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. Sheaths are round and usually hairy only near the top.

Identifying Characteristics: Additionally, the short, thick rhizomes and purple seed head are characteristics that help in the identification of this weed.

Flower Seed Head: 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.

Seed Fruit: Seed length is 1.8 -2mm.

Where Found: Purpletop is primarily a weed of hay fields, pastures, abandoned fields, and roadsides that is found from New Hampshire south to Florida. It prefers full sun, and moist dry conditions.

  • Life cycle: perennial

  • Plant type: Grass

  • Auricle: not present

  • Plant family: Poaceae

  • Leaf arrangement: rolled in bud

  • Hair surface: hairs from base to tip

  • Ligule: membrane

  • Length: less than 1 mm

  • Seed head: panicle

  • Width: less than 5 mm; 6 to 15 mm

  • Grass stem: round