This chapter concerns legumes of minor current economic significance which have not been covered previously. These include those species which have some food use but which may have other more important uses. In practice it is difficult to draw the line as grain legumes between a crop such as the winged bean, which produces edible pods, seeds and tubers, and one like the yam bean (Pachyrrhizus erosus (L.) Urban), which produces edible pods and tubers but whose mature seeds are toxic (Purseglove, 1974). Guar (Cyamopsis tetragonoloba (L.) Taub.) is another case in point (Hymowitz, 1972). This produces a mucilage-rich seed useful not only for paper-making and textiles but also in food products. The velvet beans (Mucuna spp.) merit at least a brief mention. They are capable of producing prodigious yields of pods, seeds and forage. Their seed can be used as food in times of scarcity if sufficient care is taken during preparation and cooking to eliminate two toxic amino acids (stizolobic and stizolobinic acids) which are present in the seeds.

The crops of major concern in this chapter are the hyacinth bean, the horse gram (formerly included in the genus Dolichos), the Hausa (or Kersting's) groundnut (formerly Kerstingiella) and the sword and jack beans (Canavalia spp.).

The hyacinth bean (Lablab purpureus (L.) Sweet)

Introduction

The hyacinth bean can justifiably be regarded as an under-exploited legume. Herklots (1972) observed that it is useful for soil improvement, as a cover crop and for forage.