Picão pretoBidens pilosa

Did you know?

• Bidens comes from the Latin for "two teeth," after the prongs on its seeds, and pilosa means "hairy"^{[4, 7]}.

• Each slender black seed ends in two or three stiff prongs covered in backward-pointing barbs, which hook into clothing, fur and feathers. That is how it earned names like beggar's ticks^{[6, 7, 8]}.

• In Brazil it is picão-preto; preto is Portuguese for "black," the color of its needle-like seeds^{[7, 9]}.

• In 2009, Brazil's Ministry of Health placed Bidens pilosa on its national list of plants of interest to the public health system^{[2, 10]}.

• Scientists have catalogued about 200 compounds from the plant, and a 2016 review counted 301^{[2, 11]}.

Origins and history

Picão preto is an upright, branching annual, usually 1 to 3 feet (30–100 cm) tall, with toothed leaves and small, yellow-centered flower heads^{[2, 4, 7]}. It is native to the warm Americas, from Mexico and the Caribbean south to Argentina, including Peru^[1]. It thrives wherever the ground has been disturbed: roadsides, fields, pastures and farmland^{[2, 6, 7]}.

Few plants have traveled as widely, and picão preto has done much of its traveling as a stowaway. Its barbed seeds cling to socks, animal coats and feathers and are carried to new ground^{[6, 8]}, and it is now found in almost every tropical and subtropical country, often as a weed of crops^{[2, 6]}. It is a variable plant: some forms have a ring of white petals around the yellow center, and others have none^[7].

What farmers call a weed, cooks call a green. In parts of Africa and Asia the young leaves and shoots are gathered as a vegetable, eaten raw in salads or steamed into soups and stews, and dried for storage^{[4, 6]}. The flavor is often described as resinous^{[4, 6]}. The leaves are also dried and brewed as a tea^{[2, 4]}.

Traditional uses

Clinical studies of picão preto in people are still few, but its traditional use is rich: across the tropics it has long been used both as a food and in folk tradition^{[11, 12]}.

• A leafy green and a tea

  Young leaves and shoots are eaten raw or cooked, or dried and brewed as a tea.^{[2, 4, 6]}

• Digestive comfort

  Among the Zulu of southern Africa, leaf preparations are a traditional choice for the stomach and bowels. Picão preto supports digestive comfort.*^{[2, 6]}

• A healthy inflammatory response

  In Martinique, a decoction of the whole plant is traditionally taken to support the body's natural inflammatory balance, and a leaf decoction is used the same way elsewhere. Picão preto promotes a healthy inflammatory response.*^{[2, 4, 11]}

• Healthy blood sugar

  In Martinique and China, picão preto tea or decoction has traditionally been used to help keep blood sugar in balance. It helps maintain healthy blood sugar levels already within the normal range.*^{[2, 12, 13]}

• Healthy liver function

  Brazil's Ministry of Health, in its official monograph on the plant, records the liver among picão preto's popular uses. Picão preto supports healthy liver function.*^[9]

• Immune support

  Laboratory research on picão preto has focused on how its flavonoids and other phenolic compounds interact with immune cells. Picão preto supports healthy immune function.*^[14]

Plant compounds

Picão preto contains a remarkable range of naturally occurring plant compounds. A 2011 review compiled 198 compounds from the plant, and a 2016 review counted 301^{[2, 11]}. The two largest groups are polyacetylenes, such as 1-phenylhepta-1,3,5-triyne, and flavonoids, especially aurones and chalcones^{[2, 6]}. The plant also contains caffeic acid derivatives, plant sterols and triterpenes^{[6, 11]}.