Uncaria is a genus of flowering plants in the family Rubiaceae. It has about 40 species. Their distribution is pantropical, with most species native to tropical Asia, three from Africa and the Mediterranean and two from the neotropics. They are known colloquially as gambier, cat's claw or uña de gato. The latter two names are shared with several other plants. The type species for the genus is Uncaria guianensis.

Indonesian Gambier (U. gambir) is a large tropical vine with leaves typical of the genus, being opposite and about 10 cm (3.9 in) long. The South American U. tomentosa is called Uña de Gato. Uncaria sinensis is common in China.

Uncaria was named in 1789 by Johann von Schreber in his Genera Plantarum edition 8[a] (not to be confused with books of the same title by Linnaeus, Jussieu, and others). The genus name is derived from the Latin word uncus, meaning "a hook". It refers to the hooks, formed from reduced branches, that Uncaria vines use to cling to other vegetation.

Uncaria is a member of the tribe Naucleeae, but its position within that tribe remains unresolved.

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