The leaves are 3-palmate, alternate or spiraled, and the flowers are pea-like but larger, with distinctive curved petals, and occurring in racemes. Like other legumes, Mucuna plants bear pods. They are generally bat-pollinated and produce seeds that are buoyant sea-beans. These have a characteristic three-layered appearance, appearing like the eyes of a large mammal in some species and like a hamburger in others (most notably M. sloanei) and giving rise to common names like deer-eye beans, ox-eye beans or hamburger seed.
The pods of some species are covered in coarse hairs that contain the proteolytic enzyme mucunain and cause itchy blisters when they come in contact with skin; specific names such as pruriens (Latin: "itching") or urens (Latinized Ancient Greek: "stinging like a nettle") refer to this. Other parts of the plant have medicinal properties. The plants are used in herbalism against a range of conditions, such as urinary tract, neurological and menstruation disorders, constipation, edema, fevers, tuberculosis, ulcers, Parkinson's disease and helminthiases like elephantiasis. Velvet Bean (M. pruriens) is one of the most important sources of L-dopa, a common component of nootropics ("smart drugs"); it also contains serotonin, 5-HTP, nicotine and some decidedly psychoactive compounds (see below).
Several species, such as the New Guinea Creeper (M. novo-guineensis) and M. pruriens, have brought into cultivation, although at temperatures below about 10 °C they need to be grown indoors. They are grown as ornamental plants and, locally, for food. There is interest in developing Mucuna species as a sustainable, edible cover crop. A scientific newsletter, Mucuna News, has been produced in 2001/2002 to publish the results of an international workshop focusing on improved cultivation techniques.
The genus is of some interest as a cover crop and living mulch for tropical areas; it can increase phosphorus availability after application of rock phosphate. M. pruriens was used in Native American milpa agriculture and popular as green manure in the southern USA before it was replaced by soybean in the mid-late 20th century. Mucuna is also used as a food crop, e.g. in eastern Nigeria, although the L-dopa content makes it less desirable. The plant must be processed before it can be eaten; for example, the leaves must be soaked to leach out the L-dopa. The seeds are also cracked open and soaked before they are eaten.
Mucuna pod hairs are a common ingredient in itching powder. On the other hand, the hairless parts of certain species are used by some South American shamans to make a entheogenic snuff. Presence of the hallucinogenic tryptamines 5-MeO-DMT, bufotenine and dimethyltryptamine, and supposedly the beta-Carboline 6-MeO-Harmane has been confirmed in M. pruriens, apparently the only thoroughly researched species this far.
Some Mucuna species are used as a food plant by caterpillars of Lepidoptera. These include Morpho butterflies and the Two-barred Flasher (Astraptes fulgerator) which is sometimes found on M. holtonii and perhaps others. The plant pathogenic fungus Mycosphaerella mucunae is named for being first discovered on Mucuna.