The genus Lens belongs to the Fabaceae family and includes the wild subspecies L. culinaris subsp. orientalis, the presumed progenitors L. culinaris subsp. tomentosus and L. culinaris subsp. odemensis, along with three other wild species. The taxonomy of Lens, however, remains in debate.
All species of lentil are self-pollinating annual diploids (2n=14). Two main groups of domesticated lentils are recognized on the basis of seed size: microsperma and macrosperma. The weight of 100 seeds ranges from 1.5 g for the smallest microsperma varieties to 8.0 g for large macrosperma types.
The lentil plant is a short (20–50 cm), bushy annual with weakly upright to semi-vining growth. It has a restricted root system and tends to lodge at maturity because of its weak stem. It has many soft, hairy branches with pinnately compound leaves and numerous oval leaflets.