Tulista


Tulista is a small genus of succulent plants endemic to South Africa. They were formerly included within the genus Haworthia.

Characteristics

The genus is characterised by a large size, by their stemless rosette growth form, by the yellow exudate in their non-fibrous leaves, and by their distinctive flowers with robust peduncles.

Taxonomy

The genus Haworthia was long considered problematic, and suspected of being polyphyletic. It was accordingly divided into three different subgenera: Haworthia ; Hexangulares ; Robustipedunculares. Several phylogenetic studies have confirmed this division, and shown that Haworthia actually comprises three clades that are only distantly related. Based on phylogenetic evidence, in 2013, Gordon Rowley revived the genus Tulista, first erected by Constantine Samuel Rafinesque in 1840, but long consigned to synonymy with Haworthia. However, Rowley adopted a very broad concept of Tulista, in which as well as Haworthia subgenus Robustipedunculares, the genus included Astroloba and Aloe aristata, among other taxa. Later in 2013, this broad concept was rejected by Manning et al. later, and Tulista re-circumscribed to consist of four species, a decision supported by Gildenhuys and Klopper in 2016. Rowley has subsequently defended his original approach to the genus, though it is no longer widely accepted. The same phylogenetic studies suggested that the closest relatives of Tulista were the genera Astroloba and Gonialoe.

Species

In 2014, Manning et al. recognized four species in the genus Tulista, although as of 2018, the World Checklist of Selected Plant Families accepts only three of them. All four species are highly variable, each with many different forms.




Some of the many varieties of the four species in this genus: