Seeds of Lathyrus species are toxic, containing an enzyme that interferes with collagen synthesis to cause the disease Lathyrism.

Lathyrus niger is a perennial plant with erect, self-supporting stems that grow to 30 to 80 cm (12 to 31 in).

The leaf blades are pinnate with four to eight pairs of narrow elliptical leaflets with sharp tips, entire margins and no tendrils.

The uppermost petal is known as the "standard", the lateral two as the "wings" and the lowest two are joined to form the "keel".

[1] The flowers of Lathyrus niger are pollinated by bees and smaller insects are unable to make their way to the nectar source.