Etymology -For Nicolas Esposto, a Peruvian botanist.
The genus Espostoa consists of a dozen or so species from Ecuador, Peru, and Bolivia. They are columnar plants that mostly branch at the base to form a series of stems reminiscent of a big city skyline. The most notable feature of Espostoa is presence in most species of dense, white "hair" which quite dramatically covers the stems giving them a soft, fuzzy appearance. This is just an illusion however, as underneath the soft hairs are numerous sharp spines arranged on many small ribs which circle the columns. In some species the main central spine extends well past the hair making their threatening presence obvious.
Another trait of Espostoa that is seen in sexually mature stems is the flower-bearing lateral cephalium. This is an area along the sides of the stems that produce and especially dense wool and/or bristles out of which the flowers are produced. These structures are brown or gray or white and look as if something was smeared along one side of the stem. The flowers produced are cup or bell shaped and are typically 1-2 inces (2.5-5cm) in diameter. Flowers are mostly white or rarely reddish and nocturnal.
Several species of Espostoa, are especially popular in cultivation due to their fuzzy white hairy appearance. The plants are typically sold by large commercial growers as 6-12 inch stems. However, being large columnar species, these plants do not grow nearly as vigorously in pots as they would in the ground. Plants tend to quickly fill the pots becoming pot bound and then growth slows to a crawl. As such, these plants rarely, if ever reach maturity meaning they don’t produce the cephalium and subsequently do not flower. On the other hand, those in warmer climates that can plant the species directly in the ground may indeed have plants that form a nice grouping of stems that will eventually flower.