Monograph
Black Jack (Bidens pilosa) — Uqatothi
By Silibaziso Moody
Few plants are as universally overlooked and as universally available as black jack. It grows in every garden where it has not been invited, along every path, at the edge of every maize field and vegetable plot across Zimbabwe, South Africa, and much of sub-Saharan Africa. Children know it as the weed whose needle-like seeds attach themselves to socks and trouser hems on the way home from the fields. Healers know it quite differently — as one of the most versatile and well-documented medicinal plants on the continent, with a long tradition of use stretching from the homestead garden to formal ethnobotanical research.
Bidens pilosa — called uqatothi in Ndebele, mutsine in Shona, and black jack or cobbler's pegs in English — is a fast-growing annual herb in the daisy family, reaching sixty centimetres to a metre in height, with small white flowers and the distinctive needle-like seeds that cling to clothing and animal fur. It grows in disturbed soil, garden beds, roadsides, and cultivated fields throughout the tropics and subtropics, and is so abundant that in many parts of Africa it is treated purely as a pest. This is a great underestimation of a remarkable plant.
The leaves are the most commonly used medicinal part, and they are eaten as a vegetable as much as they are used as medicine. Young black jack leaves are cooked as a relish — boiled, drained, and served with sadza or ugali across Zimbabwe, Kenya, Tanzania, and much of East and southern Africa. As food, they provide iron, calcium, vitamins A and C, and a range of polyphenols and flavonoids. As medicine, the same compounds that make them nutritious also make them therapeutically active. The leaves have demonstrated antimicrobial, anti-inflammatory, and antioxidant activity in numerous laboratory studies.
A tea made from fresh or dried black jack leaves and stems is one of the most widely used home remedies across southern Africa for malaria fever, general fever, and viral illness. The plant contains polyacetylenes and flavonoids — including quercetin and luteolin — that have shown antiplasmodial activity in laboratory studies, providing some scientific basis for its traditional use in malaria. Taken hot, the tea promotes sweating and assists the body in regulating its temperature during fever. It is also used for colds, flu, and the early stages of chest illness, where its anti-inflammatory and antimicrobial properties support the body's own recovery.
Applied externally, fresh black jack leaves are crushed and used as a poultice on infected wounds, ulcers, cuts, and insect stings. The antimicrobial compounds in the leaf — particularly the polyacetylenes — inhibit bacterial growth on the wound surface and reduce inflammation in the surrounding tissue. A cooled leaf decoction is used as a wash for skin infections, fungal conditions, and eye infections. Traditional healers across Zimbabwe and East Africa have long used a dilute black jack leaf wash as a gentle eyewash for conjunctivitis and inflamed, irritated eyes — a practice that has attracted considerable scientific attention and some supportive evidence.
Black jack has a well-established use in traditional medicine for digestive complaints — stomach pain, diarrhoea, intestinal cramps, and indigestion. A warm leaf tea taken on an empty stomach is prescribed by healers in Zimbabwe and Mozambique for gut infections and loose stools. The tannins and polyphenols in the plant help to calm gut inflammation and inhibit the growth of intestinal pathogens. The plant is also used in parts of East Africa for diabetes management, where leaf tea taken regularly is believed to support healthy blood sugar regulation — a claim that has been tested in several animal studies with promising results, though clinical evidence in humans remains limited.
Recipe
Black jack leaf tea for fever and digestive calm
Gather a small handful of fresh black jack leaves and young stems — roughly 10 to 15 leaves — or 1 heaped teaspoon of dried, crumbled leaves. Rinse well under clean water. Place in a small saucepan. Add 2 cups of cold water. Bring to a gentle simmer and cook on low heat for 10 minutes with the lid on. Remove from heat and allow to cool until comfortably warm. Strain into a cup and discard the plant material. Add raw honey and a generous squeeze of fresh lemon. Drink one cup at the onset of fever, one cup before bed, and one cup in the morning. For digestive complaints, drink one cup on an empty stomach in the morning and one cup after the evening meal. The tea is quite mild and can be drunk daily as a general tonic. Not recommended in medicinal doses during pregnancy. For an external wound wash: prepare a stronger tea using a larger handful of leaves in 2 cups of water, simmered for 15 minutes. Allow to cool completely before applying to wounds or skin infections with a clean cloth.
Black jack is the medicine hiding in plain sight — growing in every neglected corner of the garden, attaching itself to every passing ankle, colonising every patch of bare soil with cheerful persistence. It has survived centuries of being pulled up and thrown away because it is, simply, impossible to get rid of. Perhaps that is part of its teaching: that the most available medicine is often the one we are most determined to overlook. Those who have learned to pick the young leaves for the pot, or to steep them in hot water at the first sign of fever, have found in this tireless weed something that no pharmacy stocks and no one can patent — a plant that grows wherever it is needed and asks only to be recognised.
— Silibaziso Moody
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