Mucuna aimun

Wiriad.

FabaceaeSeeds/NutsPotential hazards — see below

What to Eat

Edible parts: Seeds

Seed. No more information is given, but it is almost certainly cooked. The flattened ovoid or discoid seeds are 20 - 25mm x 18 - 27mm x 10 - 12mm, contained in a seedpod 18cm long and 3cm wide. The seedpod is covered in irritant hairs.

Known Hazards

Mucuna species often possess irritant hairs on the seedpods and sometimes on the flowers and other parts. These hairs consist of 1-2 small basal cells and a large needle-like top cell. The top cell breaks off easily, piercing the skin and injecting chemical compounds that are present in the hairs. The proteolytic enzyme 'Mucunain' is said to be the active agent. The hairs can contaminate clothes or other objects, and remain active when dried, though they can be destroyed by heat. Intense itching, with reddening of the skin and small papules or urticaria occur a few minutes after contact with the hairy parts of the plant. There is no serious danger, unless the hairs get into the eye, in which case, in extreme situations, they have caused blindness. To remove the hairs from the skin, adhesive tape and washing with water and soap are considered useful. Dermatitis can be treated with corticosteroid ointment. See a doctor immediately if hairs go into the eyes.

Where to Find It

It is a tropical plant. It occurs at 2,750-2,900 m above sea level. In Papua New Guinea it occurs in the Western Highlands near Wabag.

Papua New Guinea, PNG,

Countries: Papua New Guinea

How to Identify

A climbing shrub. The twining stems can be 4 m long. The twigs have a rusty coating. The leaves have 3 leaflets. The leaflets are 6.5-15 cm long by 4-9.5 cm wide. The seed pods can be covered with irritant hairs. The pods have wide wings. The pods are 18 cm long by 3 cm wide. The seeds are 20-25 mm by 18-27 mm.

How to Grow

Mucuna species generally grow best in a shady position in a humus-rich, moist but well-drained soil. This species resembles Mucuna mollissima, Mucuna platyphylla, Mucuna tomentosa and Mucuna verdcourtii, differing from them in pod and seed characters.

Medicinal Uses

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 epithets 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 or their extracts are sold in herbalism against a range of conditions, such as urinary tract, neurological, and menstruation disorders, constipation, edema, fevers, tuberculosis, and helminthiases such as elephantiasis. In an experiment to test if M.pruriens might have an effect on the symptoms of Parkinson's disease, Katzenschlager et al. found that a seed powder had a comparable, if not more favourable, effect as commercial formulations of L-dopa, although the trial only consisted of four people per test group. M. pruriens was found to increase phosphorus availability after application of rock phosphate in one Nigerian experiment. M. pruriens was used in Native American milpa agriculture. Mucuna seeds contain a large number of antinutritional compounds. The most important is L-dopa, which the digestive system of most animals confuses with the amino acid tyrosine, causing the production of defective proteins. Other antinutrients are tannins, lectins, phytic acid, cyanogenic glycosides, and trypsin and amylase inhibitors, although all these can be removed by long cooking. M. pruriens may also contain chemicals such as serotonin, 5-HTP, nicotine, and the hallucinogenic tryptamines 5-MeO-DMT, bufotenine and dimethyltryptamine, Mucuna is not traditionally consumed as a food crop, but some preliminary experiments have shown that if the antinutrients are removed or at least brought down to safe level, the beans can be fed to livestock or people. The L-dopa content is the most important and difficult toxin to get rid of. The seeds must be extensively processed before they can be safely eaten. Diallo & Berhe found the best method was to crack open the seeds and soak them in constantly running fresh water such as under an open faucet for 36 hours, or to put them in a bag and leave in a flowing river for 72 hours, before cooking them for over an hour. Over a thousand people in the Republic of Guinea were fed a meal of Mucuna (mixed with many other ingredients) with no obvious ill effects.

References (3)

Ferns, Useful Tropical Plants
Wiriadinata, H., Ohashi, H., & Adema, F., 2016, Notes on Malesian Fabaceae (Leguminosae-Papilionoideae) 16. The genus Mucuna. Blumea 61:90-124
World Checklist of Useful Plant Species 2020. Royal Botanic Gardens, Kew