Etymology -From the Greek Cleistos, meaning closed. As in the genus Cleistocactus whose flowers seldom fully open.
Some might say that Cliestocactus is a genus of quantity over quality. That is, many of the features of this genus are small, but profuse. The stems are typically only an inch or so in diameter, but branch readily at the base to form noticeable clumps. The spines in general are likewise small and flexible, but in most cases are very numerous even to the point of obscuring the stems. This trait is continued with the flowers. Many species have flowers that resemble little tubes of lipstick or firecrackers. Yet the stems may be full of these flowers with many buds in the making. In the right conditions a plant my have flowers open every day of the year.
This genus is widespread throughout much of South America and can be found growing in large shrubby clumps mixed in with other vegetation or clamoring over boulders. Several species are extremely popular in cultivation and are among the most common of cactus in nurseries worldwide; the two most popular of all being C. strausii and C. winteri..
As is so often the case with Cactus, much further study is necessary and the exact placement of species in this genus is far from settled.