Lathyrus latifolius L. (everlasting pea, perennial sweet pea)

Pl. 398 i, k; Map 1761

Plants perennial, with rhizomes, the roots not producing tubers. Stems 80–200 cm long, trailing or climbing, usually branched, glabrous, somewhat glaucous, conspicuously winged, the wings 2–4 mm wide. Leaves with 2 leaflets, the petiole 2–6 cm long, broadly winged, the tendrils branched. Stipules 20–38 mm long, 5–12 mm wide, broadly lanceolate to ovate, the basal lobe 8–22 mm long, elliptic-lanceolate to lanceolate or triangular-lanceolate. Leaflets 4–11 cm long, 10–50 mm wide, elliptic to broadly elliptic or oblong-elliptic, angled at the base, angled to a bluntly or more commonly sharply pointed tip, the midvein sometimes extended into a minute sharp point at the very tip, glabrous, usually somewhat glaucous. Inflorescences racemes of 4–16 flowers, the stalk 8–20 cm long, the flower stalks 10–25 mm long. Calyces with the tube 4–6 mm long, glabrous, the lobes 2.0–7.5 mm long, the upper 2 short and triangular, the lowermost lobe about twice as long as the upper 2, narrowly lanceolate-triangular, the lateral lobes of the lower lip intermediate in size and shape. Corollas 18–25 mm long, purple, red, pink, or white. Filaments with the fused portion 11–12 mm long, the free portion 5–6 mm long. Ovary glabrous. Fruits 6–10 cm long, 8–10 mm wide, linear to narrowly oblong, flattened, glabrous, 10–15-seeded. Seeds 5–6 mm long, oblong in outline (more or less truncate at each end), somewhat flattened, the surface finely wrinkled, dark brown. 2n=14. June–October.

Introduced, scattered sporadically nearly throughout the state (native of Europe; introduced nearly throughout temperate North America) Edges of bottomland and mesic upland forests and banks of streams and rivers; also pastures, cemeteries, fencerows, levees, lawns, gardens, railroads, roadsides, and disturbed areas.

Lathyrus latifolius is recognized by its broadly winged stems, leaves with two, broad leaflets, very large stipules, and relatively large flowers and fruits. It is most similar to L. sylvestris, which has narrower stipules and smaller flowers and fruits. The flower color is variable, even within a population.