Black gram is an erect, fast-growing annual, herbaceous legume reaching 30-100 cm in height. It has a well-developed taproot and its stems are diffusely branched from the base. Occasionally it has a twining habit and it is generally pubescent. The leaves are trifoliate with ovate leaflets, 4-10 cm long and 2-7 cm wide. The inflorescence is borne at the extremity of a long (up to 18 cm) peduncle and bears yellow, small, papilionaceous flowers. The fruit is a cylindrical, erect pod, 4-7 cm long x 0.5 cm broad.
The green gram is a small, round olive green bean with a sweet flavor and soft texture. The mung or moong bean is the seed of Vigna radiata, belonging to the Indian subcontinent. These are commonly used in South-Asian cuisine. They are yellow in color once the skins are removed. It is mostly consumed as a main dish though sometimes it is also used to make sweet dishes. It is either cooked like a dish by boiling and adding spices, or can be made into a paste. Green gram sprouts are consumed directly with lemon and salt as a healthy snack or added to salad.
Red gram (pigeon pea) is less suitable for the tropics. The most favourable temperature range is 18-30ºC. The crop is grown at a wide range of elevation. Red gram can be grown in almost all soil types that are not very poor in lime and are not subjected to waterlogging. Optimum growth and yield are obtained in deep loam soils. Red gram can be grown as mixed crop with groundnut, paddy or tapioca or as a pure crop.