Greek aster—star, phytos—plant; referring to the star-shaped bodies.
Body solitary, globular or columnar with (3-)5-10 ribs; surface usually distinguished by distinct whitish scurfy patches, sometimes forming an ornate pattern. Flowers at apex, 3-9 cm long, scaly or wooly, yellow or yellow and red. Pericarpel with pointed scales having woolly axils. Fruit spherical, more or less dry.
Hybrids have arisen between the 4 species resulting in the intergrading of characters in cultivated plants; a range of cultivars is available
Body with few prominent ribs, appearing star-shaped from above; surface dotted with whitish scales; flowers yellow or yellow and red.
4 species from NE Mexico and S Texas.
Sadovsky & Schütz (1979).
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.