See text Cleistocactus is a genus of flowering plants in the cactus family Cactaceae, native to mountainous areas - to 3,000 m (9,843 ft)[1] - of South America (Peru, Uruguay, Bolivia and Argentina).

In some species (from the earlier genera Borzicereus and Cephalocleistocactus) they appear from conspicuous zones of heavy bristle and hair formation.

In adaptation to the pollinators (hummingbirds), the flowers are long, tubular with upright bracts, which are sometimes not or only slightly folded outwards at the tips and thus appear almost closed.

They are often slightly zygomorphic due to an upward bend near the base and/or an oblique flower border (longer or straighter at the top, shorter or more folded at the bottom).

The densely scaled fruits that emerge after fertilization are relatively small, but usually contain numerous seeds.