The butterfly-weed is also known by the nanus pleurisy-root, orange-root, Canada-root, orange swallow-wort, yellow milkweed, Indian-posy, silk-weed.
The butterfly-weed is an erect, stout, perennial herb. The stem is simple or branched near the top, hairy, very leafy, from one to two feet high. The leaves are alternate, oblong, pointed or sometime-rounded at the apex, very short-stalked or without stalks, two to six inches long. The greenish-orange flowers are arranged in terminal umbels, the stalks of which are shorter than the leaves. The seed-pods, or follicles, are very striking and characteristic of all the milkweeds. They are from four to five inches long and one to one and a half inches wide in the middle, tapering at both ends, and covered with fine hairs. The numerous seed-are flat, reddish-brown, with a long tuft of fine silky down. They may be seen in the autumn and early winter escaping from the partially opened pod and being blown some distance by the wind. The handsome orange flowers are in bloom from June to September.
Native to Canada, it is found on dry fields and banks, chiefly in the province of Ontario.
The leaves and stem are poisonous. They contain the amorphous, bitter glucoside asclepiadin. Horses and cattle avoid eating the plant, but sheep are sometimes poisoned when driven over dry districts where other herbage is scarce.
The swamp milkweed (A. incarnata L.); the common milkweed (A. syriaca L.), the showy milkweed (A. speciosa Torr.), and the oval-leaved milkweed (A. ovalifolia Dec), all natives of Canada and similar in general appearance to the butterfly weed but with opposite leaves, which is the usual arrangement with most of the milkweeds, are said to be more or less poisonous and must be viewed with suspicion until more is known of them.
Photo - F. Fyles.