Rice bean (Vigna umbellata (Thunb.) Ohwi et Ohashi)

Abstract

The rice bean (Vigna umbellata (Thunb.) Ohwi et Ohashi), a member of the leguminosae (Fabaceae) family, is an annual legume belonging to a group of little known and limitedly exploited plants. At the present time, the names Azukia umbellata (Thunb.) Ohwi, Phaseolus calcaratus Roxb., and Phaseolus pubescens B1, are considered synonyms (Duke, 1981) and this variability in nomenclature contributes towards making the rice bean less well known among people who might otherwise have some interest in it. These include students, researchers, farmers, and so on. A series of common names also increases the uncertainties about it. It has been variously referred to in English as: rice bean, red bean, climbing mountain bean, Mambi bean and oriental bean (Duke, 1981; Mejia, 1984). It has also been variously designated in Spanish as frijol arroz, frijol de arroz, judia arroz, kanime, poroto arroz (Mejia, 1984). In addition has many regional names, like tapilan, in the Philippines (Manguiat et al, 1985), and, in some countries like Brazil, there is a somewhat generalized tendency to name as adzuki bean, plants belonging to both Vigna umbellata and Vigna angularis. The confusion between rice bean and adzuki bean is quite understandable as these two species are very similar. According to Sacks (1997) analyses performed by Nguyen-Thanh-Guing showed the two species to be closely related, the only difference between them being in the cell arrrangement and seed coat.