Lathyrus polyphyllus, commonly known as Leafy Pea, is a perennial herb native to the Pacific Northwest of the United States, specifically from Washington to northern California. It thrives in a variety of habitats, including open woodlands, forest edges, and meadows. This species is particularly adapted to the cool, moist conditions found in these regions. Leafy Pea plants can reach up to 2 meters in height, supported by tendrils that grasp onto nearby structures or vegetation. The leaves are pinnately compound, with numerous pairs of oval-shaped leaflets, and the tendrils can be long, branched, and coiled, or reduced to short bristles.

Leafy Pea is notable for its attractive inflorescences, which bear up to 12 pea-like flowers in shades of purple, each about 1 inch wide, typically blooming in late spring to early summer. The flowers are moderately showy and can add a splash of color to naturalistic plantings. The fruit is a dehiscent legume pod that releases peas when mature. In cultivation, Leafy Pea is valued for its ability to fix nitrogen in the soil, improving soil fertility. It is often used in restoration projects, as well as in native plant gardens for its ecological benefits and ornamental qualities. It prefers well-drained soils, moderate water, and can tolerate both full sun and part shade. While generally low-maintenance, it can be susceptible to fungal diseases in overly moist conditions.CC BY-SA 4.0