1. Aristolochia serpentaria L. (Virginia snakeroot)

A. serpentaria var. hastata (Nutt.) Duch.

Pl. 219 h, i; Map 912

Plants herbaceous perennials with rhizomes. Aerial stems 15–60 cm long, erect or ascending, sometimes appearing slightly zigzag, glabrous or hairy. Petioles 0.5–3.5 cm long. Leaf blades 5–14 cm long, lanceolate to oblong-ovate or narrowly triangular, tapered to a sharply pointed tip, variously cordate, arrowhead-shaped, or truncate at the base, the main veins pinnate above a somewhat palmate base, the undersurface sometimes hairy. Flowers solitary at the tips of short, scaly branches produced near the base of the aerial stem. Calyx 1–3 cm long, hairy on the outer surface, the tube hooked or S-shaped, expanded at both ends, purple to brown above a white to tan base, the lobes ascending to spreading, unequal, shallow, broadly triangular, purple and glabrous on the inner (upper) surface. Fruits 0.8–1.8 cm long, globose or nearly so, 6-ribbed. Seeds 4–5 mm long, concave and with a longitudinal ridge on one side, rounded on the other, ovate in outline, brown, with a lighter pattern of wrinkled ridges and finely pebbled bumps. 2n=28. May–July.

Scattered to common in southern and central Missouri; rare to absent in the northern third of the state (eastern U.S. west to Iowa, Kansas, and Texas). Bottomland and mesic upland forests, rarely dry upland forests.

The rootstocks of A. serpentaria are harvested for the medicinal trade under the names Virginia snakeroot and serpentary. Native Americans, pioneers, and herbalists have made a tonic from the dried rhizomes as treatment for a variety of problems, including general pain, toothache, fevers, colds, rheumatism, worms, snakebite, and as a diuretic. Readers should note the statement above on possible carcinogenic compounds and also that overuse can lead to gastric distress.

Occasional plants may be encountered with somewhat smaller flowers that apparently do not open. Such flowers have been suggested to reproduce cleistogamously. Plants with narrower leaves have been encountered rarely in Dent and Dunklin Counties and have been referred to var. hastata, a trivial variant that occurs sporadically nearly throughout the range of the species.

The closely related A. reticulata occurs from Texas and Louisiana to Oklahoma and Arkansas and eventually may be found growing in southwestern Missouri. It differs from A. serpentaria in its short-petiolate leaves with the bases appearing to clasp the stems and the tips blunt to rounded, and in its slightly smaller seeds (3–4 mm long).