WordNet (r) 3.0 (2006):

Vigna caracalla
    n 1: perennial tropical American vine cultivated for its racemes
         of showy yellow and purple flowers having the corolla keel
         coiled like a snail shell; sometimes placed in genus
         Phaseolus [syn: snailflower, snail-flower, snail
         flower, snail bean, corkscrew flower, Vigna
         caracalla, Phaseolus caracalla]