Look up Cowpea aka Ginger Bean in Chinese Legume Names. There is only one standard pinyin jiāng for the word cowpea, and cowpea is homophonic with ginger.

Cowpeas are divided into two species, long cowpeas and rice cowpeas, and belong to the legume family, Cowpeas are leguminous annuals, twining, herbaceous vines or suberect herbs of the family Leguminosae, sometimes apically twining, with subglabrous stems and pinnately compound leaves with 3 leaflets. Stipules lanceolate, ca. 1 cm, decurrent into a short spur where inserted, wired. Leaflets ovate-rhombic, 5-15 centimeters long, 4-6 centimeters wide, apex acute, sides entire or subentire, sometimes lavender, glabrous.