This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Native. Perennial. Propagates by seeds.
Time of bloom: June to September.
Seed-time: July to October.
Range: New Brunswick to Minnesota, southward to Florida and
Mexico; also in California. Habitat: Damp soil; wet meadows, swamps, waste places.
Often found growing in company with the Smartweed, and more troublesome as a weed because perennial. Stems slender, erect or decumbent, one to three feet long, usually simple or with a few branches near the top, smooth or with appressed, bristly hairs. Leaves narrowly lance-shaped, acute, bristly-hairy on the midribs beneath, ciliate, not glandular, and not acrid; sheathing stipules narrow and bristle-fringed. Spikes terminal, erect, narrow, often interrupted below; calyx pink or greenish white, with eight stamens and with style deeply three-parted. Achenes three-angled, smooth, and shining.
Drainage and cultivation where practicable; frequent and close cutting for the purpose of starving the perennial roots and preventing the production of seed. Small areas may be grubbed out.