Tulista is a small genus of succulent plants in the family Asphodelaceae (order Asparagales), endemic to the Cape Provinces of South Africa. The genus comprises four accepted species — Tulista pumila, T. marginata, T. minor, and T. kingiana — all of which are highly variable, with each species exhibiting numerous distinct forms.
These plants were long classified within the genus Haworthia, but phylogenetic studies demonstrated that Haworthia as traditionally conceived is polyphyletic, comprising three distantly related clades. In 2013, Gordon Rowley revived the genus Tulista, originally erected by Constantine Samuel Rafinesque in 1840 but long treated as a synonym of Haworthia. Manning et al. subsequently re-circumscribed Tulista to its current four-species composition, a delimitation supported by later work. The genus corresponds to Haworthia subgenus Robustipedunculares, and its closest relatives are the genera Astroloba and Gonialoe.
The four species occupy distinct ranges within the Western and Eastern Cape. T. pumila, the largest species, grows in the Robertson Karoo of the Western Cape and bears raised white tubercles on darker-coloured leaves. T. marginata, the second-largest, ranges eastward to Riversdale and is particularly valued as an ornamental for its clear leaf margins and keel. T. minor occupies coastal renosterveld habitats and is densely covered with tubercles, typically with a blue-green colouration. T. kingiana, the rarest of the four, is restricted to the vicinity of Mossel Bay and has smooth, glossy tubercles with a yellow-green colour.
Etymology
The genus name Tulista was originally coined by the American polymath Constantine Samuel Rafinesque in 1840. It was long treated as a synonym of Haworthia until Gordon Rowley revived it in 2013 on the basis of phylogenetic evidence showing that Haworthia sensu lato was polyphyletic.
Distribution
All four species of Tulista are endemic to the Cape Provinces of South Africa. T. pumila is the westernmost species, occurring in the Robertson Karoo of the Western Cape; T. marginata extends eastward from there to Riversdale; T. minor grows in renosterveld vegetation near the southern coast; and T. kingiana is the rarest and most easterly, restricted to the vicinity of Mossel Bay.
Taxonomy Notes
Tulista was originally placed in synonymy with Haworthia after Rafinesque described it in 1840. Molecular phylogenetic studies revealed that Haworthia comprised three distantly related clades, corresponding to subgenera Haworthia, Hexangulares, and Robustipedunculares. In 2013 Rowley revived Tulista for a broad group including Astroloba and Aristaloe aristata, but Manning et al. later rejected this and restricted the genus to the four species of the Robustipedunculares clade. Gildenhuys and Klopper supported this narrower circumscription in 2016. The closest relatives of Tulista are Astroloba and Gonialoe.
