Commemorating Nicholas E Esposto, early 20th century Peruvian botanist.
Body shrubby to tree-like, potentially several metres tall, cylindrical to columnar with mostly about 18-30 ribs. Areoles of the flowering region with wool and spines forming a distinct region (cephalium) where the ribs are also reduced. Flowers mostly nocturnal, lateral, tubular to bell-shaped; stamens at the base of the throat on a rim above the nectar chamber; flower tube short with small, pointed scales with hair in their axils; spring to summer. Fruit more or less spherical or broadest towards the tip, mostly pink, naked or with tufts of hair.
The 3 most commonly cultivated species are keyed out in the key.
Mostly columnar cacti with a dense covering of wool and with knobby lateral cephalia.
About 10 species from Peru, Bolivia and S Ecuador.
Source: (1997). Cactaceae. In: . Horticultural Flora of South-eastern Australia. Volume 2. Flowering plants. Dicotyledons. Part 1. The identification of garden and cultivated plants. University of New South Wales Press.
