Cleistocactus

Cleistocactus is a genus of flowering plants in the cactus family Cactaceae, native to mountainous areas - to - of South America (Peru, Uruguay, Bolivia and Argentina). The name comes from the Greek kleistos meaning closed because the flowers hardly open.

==Description== The plants of the genus are slender stem succulents that are tall, mostly slender and often many-branched up to about 3 m high. They usually form basally branching shrubs, rarely they branch higher and form small trees. The shoots stand upright and then often hang over as they get older; they usually lie down with their ends rising up; more rarely they grow hanging. They usually have many ribs, closely set areoles and spines. The areoles on the ribs usually have many fine, hair-like spines with a few firmer spines in between; the spines are rarely longer and coarse.