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: July to September.
Seed-time: September to November.
Range: Massachusetts to Minnesota, southward to the Gulf of
Mexico. Habitat: Dry, sandy soil; fields, meadows, pastures, roadsides, and waste places; most troublesome in the Southwest.
Pastures rankly infested with this weed are nearly useless, for it is strongly cathartic and when eaten in any quantity by cattle and sheep they "scour" very badly; grazing horses are sickened in the same way and must be relieved by change of forage. Young stalks are often mown and baled with the hay of infested meadows, causing the same trouble when the fodder is used in winter.
The plant is low and spreading, often branching wider than its height of one or two feet. When young the stem may be sparsely hairy, but usually it is smooth and pale green. Leaves pin-nately compound, composed of ten to fifteen pairs of small, entire, lance-shaped leaflets each tipped with a sharp bristle; petioles short, with persistent, awl-shaped stipules and having near the base a sessile gland. The leaves are sensitive, and at night "go to sleep" by folding their blades face to face and drooping against the stalk. Flowers large, often more than an inch across, lifted on slender peduncles from the upper axils, singly or in clusters of two or three; they are bright golden yellow, but often two or three of the rounded petals are spotted with purple at the base, and usually six of the anthers are purple and four are yellow. Pods slender, about two inches long, slightly hairy; when ripe, they split apart with a slightly twisting action by which the seeds are thrown a short distance from the parent plant; so that next year, where one weed grew there will be a little patch. (Fig. 158.)
Fig. 158. - Partridge Pea (Cassia Chamoecrista). X 1/3.
Prevent development of seed. Postpone all other work for a day and cut the Partridge Pea patches on noting the first golden bloom. Repeat the operation with the new growth which follows, and as soon as all dormant seed in the ground has stirred into life and been given like treatment the trouble will be ended. New infestations should be promptly pulled or cut before any seed is formed. Ground on which plants have been allowed to mature and scatter seeds should be burned over in order to destroy them.