Vigna mungo, known as black gram, black lentil, white lentil, black matpe bean, urad, urad dal, udad dal, urd bean, urd, urid, maas (in Nepali), or උඳු (Sinhala, đậu đen Vietnamese, literally: black bean), is a bean grown in southern Asia. It is largely used to make dal from the whole or split, dehusked seeds. It, along with the mung bean, was placed in Phaseolus, but has since been transferred to Vigna. At one time it was considered to belong to the same species as the mung bean. The product sold as "black lentil" is usually the whole urad bean or urad dal. The product sold as "white lentil" is the same lentil with the black skin removed.
Black gram originated in India, where it has been in cultivation from ancient times and is one of the most highly prized pulses of India. The coastal Andhra region in Andhra Pradesh is famous for black gram after paddy. The Guntur District ranks first in Andhra Pradesh for the production of black gram. Black gram has also been introduced to other tropical areas mainly by Indian immigrants. In Bengal it is made with a preparation named as Biulir Dal.
It is an erect, suberect or trailing, densely hairy, annual herb. The tap root produces a branched root system with smooth, rounded nodules. The pods are narrow, cylindrical and up to six cm long. The bean is boiled and eaten whole or, after splitting, made into dal; prepared like this it has an unusual mucilaginous texture. Ground into flour or paste, it is also extensively used in South Indian culinary preparations, such as dosa, idli, vada, and papadum. When used this way, the white lentils are usually used.
It is nutritious and is recommended for diabetics, as are other pulses. It is very popular in the Punjabi cuisine of India and Pakistan, where it is known as sabut maash, an ingredient of dal makhani. In Malayalam, it is known as uzhunu (ഉഴുന്ന്), Telugu, it is known as minumulu (మినుములు), in Kannada as uddina bele (ಉದ್ದಿನ ಬೇಳೆ), in Tamil as ulunthu(உளுந்து), and in Oriya as biri dali.
Vigna mungo is used in traditional Indian(Ayurveda) medicine. Pharmacologically, extracts have demonstrated immunostimulatory activity.