The pistil has an ellipsoid stigma, 1.5 mm. A large woody vine or creeping shrub, typical of primary forest, but also found in disturbed forest and rarely in secondary forest. The external bark has superficial longitudinal fissures, and the internal bark is fibrous, with the ground bark the color golden yellow. The sap is watery and astringent in taste. The terminal branchlets are quadrangular and yellow-green in color.
Flowers are bisexual, actinomorphic and sessil.
Crop Culture Ecology Cat s claw is sometimes cultivated or managed in tropical forests of South America. U. guianensis may be cultivated in secondary forests with full sunlight, but U. tomentosa requires more shade, as it is found more often in primary forest. In the traded product, these chemotypes have largely been ignored. The subject of which chemical profile is better, the stem vs. the root, is largely irrelevant due to the difficulty of trade in the root material of cat s claw. The leaves have not been found useful commercially, however, there are groups in Lima who are researching this for possible commercial uses.