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 Hampshire to Ontario and Michigan, southward to
Florida, Kansas, and Texas. Habitat: Swamps, low meadows, banks of streams, and ditches.
Roots fascicled, spindle-shaped, rather thick and fleshy. Stems two to three feet tall, erect, round, smooth, with a strong bark and many branches. Leaves alternate, entire, with marginal veins, smooth or nearly so, pointed at both ends, two to four inches in length, sessile or with very short petioles. Flowers solitary in the axils on very short peduncles; they are nearly an inch broad, with four light yellow, rounded petals, between which show the four-pointed, spreading, leaf-like lobes of the calyx, about as long. When plucked, the petals almost always fall away; stamens four, inserted with the petals; ovary four-celled. Capsules smooth, square, with winged angles and rounded base, about a quarter-inch high; the seeds become loose and rattle about in them when the plant is shaken. These seed-vessels readily float on water and are often blown far on crusted snow. (Fig. 204.)
Drainage of the ground, followed by a cultivated crop, very thoroughly tilled. Or starvation of the perennial roots by close and frequent cutting throughout the growing season.