Haworthiopsis coarctata

Haworthiopsis coarctata, formerly Haworthia coarctata, is a species of flowering succulent plant from the Eastern Cape Province, South Africa and naturalized in Mexico. It is one of the species of "Haworthiopsis" that is commonly cultivated as an ornamental.
Description.
"H. coarctata" grows in large clumps in its natural habitat, with long stems packed with robust succulent leaves. It is normally dark green but sometimes acquires a rich purple-red when in full sunlight.
It is frequently confused with "Haworthiopsis reinwardtii", which occurs just to the east of its natural range. However "H. coarctata" has smaller, smoother and rounder tubercles on its leaves (those of "H.reinwardtii" are sometimes larger, flatter and whiter). "H. coarctata" also usually has much wider, fatter leaves.
Forms and varieties.
This is a variable species, and several forms and varieties are recognised. Several are listed below: 
Cultivation.
"Haworthia coarctata" has received the Royal Horticultural Society's Award of Garden Merit.