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 slender, creeping rootstocks. Time of bloom: June to July. Seed-time: August to September. Range: Ontario to Manitoba, southward to Florida, Texas, and
Mexico. Habitat: Dry upland meadows, pastures, and woodland borders.
It is fortunate that this plant has a preference for dry, sandy, and sterile soil, for the long, slender, and very tough rootstocks, which have given it the common names of Catgut and Devil's Shoe-strings, cause it to grow in large clumps or patches and make it very difficult to exterminate where it is well established. (Fig. 170.) .
Stems erect, tufted, simple, ridged, hard and woody at the base, one to two feet high, leafy to the top. The whole plant is covered with soft, silky, whitish hairs, especially when young, making the foliage ashen-gray or hoary. Leaves alternate, odd-pinnate, with seventeen to twenty-nine narrowly oblong, entire leaflets, about an inch in length, the midrib of each projecting slightly as a minute bristle at the tip. At night the leaves take a position as for slumber, turning on their bases and folding themselves along the stem. Flowers in short, crowded, terminal racemes; each blossom is nearly an inch long, with hairy, five-lobed calyx,
Fig. 170. - Hoary Pea (Tephrosia virginiana). X 1/4 a rounded, yellowish white standard tinged with purple, a rosy pink keel, and reddish purple wings; the standard is softly hairy on the back. Pods one or two inches in length, flattened, often somewhat curved, densely hairy, and many-seeded. Wild turkeys are said to search for and fatten on the peas, though the plant has the reputation of being poisonous. The Indians used its string-like rootstocks for a vermifuge, and Pammel1 states that it was used also for poisoning fish.
Prevent seed production and starve the rootstocks by cutting the stems close to the ground in early summer. Cultivate and enrich the soil.