Lathyrus palustris L.

Slender rhizomatous climbing perennial, to 1 m, the stem often winged; stipules semisagittate, often serrate; lfls 4–8(10), linear to elliptic, 2–8 cm × 3–20 mm; peduncles about equaling the subtending lf, with a raceme of 2–6(–9) red-purple (whitish) fls 12–20 mm; cal distinctly oblique, the lower lobes much longer than the upper; 2n=42. Wet meadows, swamps, shores, and wet woods; circumboreal, in Amer. s. to N.J., Pa., O., Ind., Mo., Colo., and Calif. June, July. Var. palustris, with winged stems and usually 6–8 lfls, occurs throughout the range of the sp. Typical var. palustris is glabrous or nearly so; a pubescent form, called var. pilosus (Cham.) Ledeb., has the same distribution but is more common along the seacoast; it is only doubtfully significant. Forms with narrow and broad lfls occur in both typical var. palustris and the hairy phase. The well marked but still not wholly distinct var. myrtifolius (Muhl.) A. Gray, consistently glabrous, with wingless (but sometimes acutely ridged) stems and usually 4(6) lfls that tend to be shorter (2–4 cm), broader, and more rounded than in var. palustris, occurs chiefly from N.Y. to Wis. and Ill., especially about the Great Lakes.

A temperate plant. It likes moisture. In China it grows in marshes and rice fields. It grows from sea level to 3,500 m above sea level. In Sichuan and Yunnan.

CAUTION: Poisonous unless treated. It can cause the legs to become paralysed. The seeds are eaten. In small quantities they do not cause problems.

Can be grown by seedlings. Seeds needs soaking.