Haworthiopsis nigra

Haworthiopsis nigra is a small, dark-leaved succulent from the Great Karoo of South Africa, where it grows wedged beneath rocks and shrubs across the Western, Northern, and Eastern Cape provinces. Long sold under its old name Haworthia nigra, the species was moved to the genus Haworthiopsis in 2014 after genetic work separated the harder-leaved Haworthia species into their own group. Its triangular, pointed leaves are arranged in three neat tiers along a short stem, each one ridged with raised white tubercles and ranging in colour from dull olive to almost black depending on sun exposure — plants in brighter positions colour up darker. It does best in an open, well-ventilated terrarium with gritty soil, low humidity, and a long dry winter rest.