Haworthiopsis nigra typically grows its leaves in three tiers (though some varieties have multifarious leaf arrangement). The leaves, which are a very dark green to brownish black, are covered in dark tubercles, and are packed densely along its stems.
Taxonomy
The species was formerly placed in Haworthia subgenus Hexangulares. Phylogenetic studies have demonstrated that subgenus Hexangulares is actually relatively unrelated to other Haworthias (being more closely related to Gasteria). The species was therefore moved to Haworthiopsis.[1][2]
Distribution
This species extends across the southern part of South Africa. The variety "diversifolia" occurs in the west of its range, in the Western Cape Province around Loeriesfontein. The type variety "nigra" occurs to the east of its range, in the Eastern Cape as far east as East London.
Within this range, it typically grows in very well-drained sandy soil, usually under a bush or rocks which serve as partial protection from the sun.
↑Manning, John; Boatwright, James S.; Daru, Barnabas H.; Maurin, Olivier; van der Bank, Michelle. A Molecular Phylogeny and Generic Classification of Asphodelaceae subfamily Alooideae: A Final Resolution of the Prickly Issue of Polyphyly in the Alooids? Systematic Botany, Volume 39, Number 1, March 2014, pp. 55-74
