BOTANICAL NAME :-Vigna mungo

Dal also referred to as urad dal, urd bean, urd, urid, black matpe bean, black gram, black lentil (not to be confused with the much smaller true black lentil (lens culinaris)), or white lentil (Vigna mungo), 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 been transferred to Vigna. It was at one point considered to belong to the same species as mung bean.
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. It has also been introduced to other tropical areas mainly by Indian immigrants.

It is an erect, sub-erect 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 6 cm long. The bean is boiled and eaten whole or after splitting into dal; prepared like this it has an unusual mucilaginous texture. Ground into flour or paste, it is also extensively used in culinary preparation like dosa, idli, vada, and papad. When used this way, the white lentils are usually used. The white lentils are called “ulundhu” in Tamil.

It is very nutritious and is recommended for diabetics, as are other pulses. It is very popular in Punjabi cuisine of India and Pakistan where it is known as “maanh”.
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.

Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Fabales
Family: Fabaceae
Subfamily: Faboideae
Tribe: Phaseoleae
Genus: Vigna
Species: V. mungo

Red (kidney) beans

The kidney bean with its dark red skin is named for its visual resemblance to a kidney. The kidney bean is also known as the red bean, although this usage can cause confusion with other red beans. Red kidney beans (rājmā in Hindi and Punjabi) are an integral part of the cuisine in northern region of India. Sometimes kidney beans are used in the red beans and rice of Louisiana Creole cuisine. Other times small red beans are used. Small red beans are noticeably smaller and darker than kidney beans. They have a smoother taste and are preferred for Cajun cuisine. Small kidney beans used in La Rioja, Spain, are called Caparrones.