Greek pedion—plain, referring to the Great Plains habitat of the type species.
Body low-growing, solitary or in clusters, tuberculate. Flowers bell-shaped, borne more or less at the tip of the body. Pericarpel mostly without structures; flower tube short, occasionally with a few small scales. Fruit mostly without structures except for the persistent flower parts which are shed and form a lid to the fruit, dull-coloured.
The 2 more commonly cultivated species are keyed out in the key. They are generally collectors' items.
Dull-coloured dry fruits opening along a vertical slit in the ovary wall folding back like French windows, the top opening like a lid.
About 6 species from the W and SW North America (Colorado Plateau, Columbia River Basin, Great Basin and the Rockies).
Heil et al. (1981).
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.
