Lathyrus tuberosus L. (tuberous vetchling)

Map 1765

Plants perennial, with rhizomes, these producing small tubers. Stems 30–100 cm long, trailing or climbing, usually branched, glabrous, 2-angled but not winged. Leaves with 2 leaflets, the petiole 0.3–1.0 cm long, unwinged, the tendrils unbranched or branched. Stipules 3–12 mm long, 1–3 mm wide, lanceolate, the basal lobe 1–2 mm long, linear to narrowly oblong-triangular. Leaflets 1.5–4.0 cm long, 5–13 mm wide, lanceolate, narrowly lanceolate, narrowly elliptic, narrowly oblanceolate, or narrowly obovate, angled at the base, angled or slightly tapered to a bluntly or sharply pointed tip, the midvein sometimes extended into a minute sharp point at the very tip, glabrous. Inflorescences dense racemes of 2–10 flowers, the stalk 5–8 cm long, the flower stalks 3–5 mm long. Calyces with the tube 3–4 mm long, glabrous, the lobes 3–5 mm long, the upper 2 lobes slightly shorter than the lower 3, all triangular to broadly lanceolate-triangular. Corollas 10–16 mm long, reddish purple. Filaments with the fused portion 6–7 mm long, the free portion 4–5 mm long. Ovary glabrous. Fruits 1.5–4.0 cm long, 3–5 mm wide, narrowly oblong, flattened, glabrous, 1–5-seeded. Seeds 4–5 mm long, ovoid or oblong-ellipsoid to more or less globose or broadly oblong in outline, not flattened, the surface finely wrinkled, reddish brown to grayish brown or dark brown. 2n=14. June–July.

Introduced, uncommon, known thus far only from Dallas County (native of Europe; introduced widely in the northern U.S., Canada). Fence rows and open, disturbed areas.

Lathyrus tuberosus is recognized by its wingless stems and the production of small tubers along the slender rhizomes. The tubers can be cooked and eaten. It was first reported for Missouri by Ladd (1994).