When European settled in southern Africa in the latter half of the seventeenth century, the Age of Enlightenment has already spread its wings, exciting and challenging the intellect, refuting the tenets of ignorance and superstition. More widespread education and the availability of printed books had taken learning out of the monasteries, while the natural curiosity of man had been aroused by tales of brave new worlds beyond the sea – worlds with, among other things, wondrous people, animals, and plant life.
The 17-18th Centuries
1695. The first reference to the plants, known today as Haworthia, occurs in letters sent to Holland by Hendrick Bernard Oldenland, who was superintendent of the gardens of the Dutch East India company. He listed 28 “Aloes”, and of these 4 were plants we now consider to be Haworthias. Descriptions of these plants first appeared in print in 1703 in Commelin’s Praeludia Botanica.
1701. The first published references concerning Haworthias appeared in Jan Commelin’s Horti Medici Amstrelodamensis Rariorum Plantarum. The illustrations were made in Amsterdam from plants growing in the Hortus Medicus. 4 Haworthia plants in the species H. retusa, T. marginata, T. pulima are included.
1753. The Species Plantarum of Carl Linnaeus is taken as the starting point of our modern binomial nomenclature for flowering plants. Linnaeus’s genus Aloe covered Haworthia. 9 “Aloes” were included, 3 of which are now classified as Haworthias in the species H. retusa, H. viscosa, and T. pulima.
The 19th Century
1804. Adrian Haworth published “A new arrangement of the genus Aloe, with a chronological Sketch of the progressive Knowledge of that Genus, and of other succulent Genera.” in Transactions of the Linnean Society of London. He described a number of new species, nine of which were Haworthias. The latter and some Astrolobas were grouped in his section Parviflorae, indicating that he recognized a difference between them and the typical Aloes.
1809. Henri Duval, in his publication “Plantae succulentae in Horto Alenconio”, separated the genera Haworthia and Gasteria from Aloe.
1812-27. Haworth accepted Duval’s newly erected genera Haworthia and Gasteria in his Synopsis Plantarum Succulentarum. And for the first time, he added hints for the cultivation of succulent plants. After Haworth’s death (1833), there was a tendency to revert back to the Linnaean sense of Aloe, a situation that remained for ~50 years.
1880. John Baker published “A synopsis of Aloineae and Yuccoideae” in the Journal of the proceedings of the Linnean Society. Botany. This was the first recognition of Haworthia, as a genus, since Haworth.
The 20th Century
1908. Alwin Berger published “Liliaceae-Aloineae-Asphodaleceae” in Das Pflanzenreitch. This was the first monograph on the Aloaceae, and, therefore, Haworthia too.
1928-45. Karl von Poellnitz described over 200 new species and varieties. Most of his work appeared in Fedde’s Repertorium. In the century between Haworth and von Pollnitz, the genus Haworthia increased in size only slightly. In the two decades which von Poellnitz was active, the number of species was more than doubled.
1938-51. A.J.A. Uitewaal published a total of 22 papers that appeared in Succulenta and other journals. He observed that a natural division of the genus could be made based on floral characteristics and proposed 4 sections: Triangulares, Hexangulares, Robustipedunculatae, and Gracilipedunculatae.
1985. Charles Scott published his most familiar contribution to Haworthia literature, The Genus Haworthia, based on his extensive fieldwork.
1976-99. Bruce Bayer published 3 books: Haworthia Handbook, The New Haworthia Handbook, and Haworthia Revisited. He has seen kept the number species to manageable and understandable proportions. He established 3 subgenera: Haworthia, Hexangulares, and Robustipedunculatae, deriving partly from the concept of Uitewaal.
The 21th Century
2013. Gordon Rowley proposed to rise 3 Haworthia subgenera from Bayer to separate genera Haworthia, Haworthiopsis, and Tulista.
2014. John Manning et al. produced a phylogeny based on 11 Aloe genera and divided the genus Haworthia into 3 separate genera, accepting the genera names proposed by Rowley. It has some adjustments to the members in previous Bayer’s subgenera classification.