This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Native. Annual. Propagates by seeds.
Time of bloom: June to September.
Seed-time: August to November.
Range: Nova Scotia to Minnesota, southward to Florida and
Texas. Habitat: Rich, moist soil; a common barnyard weed and a special nuisance in clover fields.
The seeds of this weed, when an impurity in those of clover, are so nearly of the same size and weight that they are almost impossible to remove. Professor Selby, of the Ohio State Experiment Station, wisely remarks that "the time to remove such seeds is before the clover is cut."
Stem six inches to two feet high, erect, somewhat hairy, often purplish or brown. Leaves alternate, two to four inches in length, long ovate, thin, dark green, often turning to a coppery brown, coarsely toothed except near the base. In their axils are the inconspicuous greenish flowers, male and female separate, but growing from the same point, the staminate ones being lifted on a tiny spike, the fertile ones just below, and both supported by a large, leafy, cut-lobed bract, longer than either, usually about a half inch high. Capsules three-celled, each cavity containing one dull reddish brown or gray seed, egg-shaped, and easily crushed between the fingers, which is the reason why they are called Wax-balls. (Fig. 185.)
Pulling or cutting the weeds before any seeds have matured. Land badly fouled by the seeds should be put to a profitable and thoroughly tilled hoed crop for a season.