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 and by rootstocks.
Time of bloom: July to September.
Seed-time: Late August to November.
Range: New York to Manitoba, southward to Florida and Louisiana.
Habitat: Rich soil; fields, meadows, waste places.
This plant is very variable, but is in all its forms a bad weed because of its fleshy, creeping rootstock. Stem eighteen inches to three feet tall, slightly angled, fork-branched, covered with ap-pressed hairs or sometimes nearly smooth or in some forms somewhat glandular. Leaves long-ovate to lance-shaped, tapering at both ends, usually with a few roundish, irregular teeth on each side but often entire, rather thin, light green. Flowers more than a half-inch broad, the corolla sulfur-yellow with purplish brown spots, the stamens erect with deep yellow anthers; the calyx at first hairy but as it enlarges becoming nearly smooth, pyramidal-ovoid, five-angled, and deeply sunken around the peduncle. Fruit reddish, about a half-inch in diameter.
Means of control the same as for Prairie Ground Cherry.