Urd is closely related to V. radiata, the mung bean. Nomenclature adds to the possibilities of confusion. Thus it is urd which has the specific name mungo, which might be expected to belong to the mung bean. Moreover urd beans are not all black (as their alternative name ‘black gram’ would suggest), but may be green (the green ones are smaller and ripen later than the black ones); and green gram is one of the alternative names for mung bean. However, any possible confusion is dispelled when the two small pulses are peeled and split, thus becoming dal instead of gram, for the urd is then seen to be white inside while the mung is yellow.