Rebutia is a genus of flowering plants in the family Cactaceae, native to Bolivia and Argentina. The limits of the genus have varied widely, depending on whether genera such as Aylostera and Weingartia are included or treated separately. , Plants of the World Online accepted only three species of Rebutia. A very large number of plants that have been treated in cultivation as species of Rebutia are now generally regarded as varieties, forms or synonyms of a much smaller number of species, or have been transferred to other genera. Plants treated as Rebutia are generally small, colorful cacti, globular in form, which freely produce flowers that are relatively large in relation to the body. They have no distinctive ribs, but do have regularly arranged small tubercles. They are considered fairly easy to grow and they may produce large quantities of seeds that germinate freely around the parent plant.
Taxonomy The genus was designated in 1895 by Karl Moritz SchumannMonatsschrift für Kakteenkunde, 5: 102, 1895 and named after Pierre Rebut (1828–1902), a French cactus nurseryman. The type species is R. minuscula, which has been in cultivation since 1887.N. L. Britton, J. N. Rose, The Cactaceae, Washington, 1920, vol.III, p.45.Archives départementales du Rhône. death record. Chazay-d'Azergues. 14 March 1902.
Historical limits of the genus There has been considerable debate about the extent of the genus. In the middle of the twentieth century there was a tendency to separate groups of plants within Rebutia as new genera, e.g. Mediolobivia, whereas towards the end of the century the reverse tendency predominated, with genera previously regarded as separate, such as Weingartia, being subsumed within Rebutia. At the beginning of the twenty-first century there was a broad consensus, as reflected in Kew's list of Vascular Plant Families and Genera, that the following genera should be regarded as synonyms of Rebutia:
(The generic names Bridgesia, Spegazzinia, Echinorebutia, Eurebutia, Mediorebutia, Neogymnantha and Setirebutia are invalid, the first two because they are homonyms of Bridgesia Bert. ex Cambess. and Spegazzinia Backeb. respectively, the remainder for lack of any valid publication. Some of these are nevertheless valid names for subdivisions of the genus.)
The history of the taxonomic treatment of the genera Rebutia, Aylostera, Weingartia, Sulcorebutia and Cintia is summarized below.
K. Schumann Britton & Rose Spegazzini A. V. Frič 1895 1896 - 1921 1922 1923 1932 - 1938 Rebutia genus novum Echinocactus Echinopsis Rebutia renovation Rebutia Rebutia Rebutia Rebutia Aylostera genus novum Digitorebutia, Cylindrorebutia, Echinorebutia, Setirebutia, Hymenorebutia, Scopaerebutia C. Backeberg Donald ICSG Anderson Rowley Mosti & Papini 1966 1975 2001 2009 2011 Rebutia K. Schum. Rebutia sectio Rebutia Rebutia Rebutia subg. Rebutia Rebutia Aylostera Speg. Rebutia sectio Aylostera Rebutia Aylosterasubg. Aylostera Aylosterasubg. Aylostera Mediolobivia Backeb. Rebutia sectio Setirebutia, Digitorebutia, Cylindrorebutia Rebutia Aylosterasubg. Mediolobivia Aylosterasubg. Mediolobivia Weingartia Werderm.syn.Spegazzinia Backeb. Weingartia Rebutia Rebutia subg. Weingartia Weingartia Sulcorebutia Backeb. Sulcorebutia Rebutia Rebutia subg. Sulcorebutia Weingartia incl. Cintia
The variation in the treatment of the genus is illustrated by the difference between Anderson in 2001, who synonymized genera including Aylostera and Weingartia with Rebutia, thereby creating a genus with as many as 41 species, and Mosti et al., who in 2011 separated Aylostera and Weingartia (including Cintia and Sulcorebutia) from Rebutia. , Plants of the World Online agreed with Mosti et al. in keeping Aylostera separate, and also merged Cintia and Sulcorebutia into Weingartia, resulting in Rebutia having only three species.
Phylogeny Molecular phylogenetic studies showed that when broadly circumscribed, the genus Rebutia was polyphyletic. Sulcorebutia and Weingartia were kept as separate genera in a 2007 study whose summary cladogram for those species studied is shown below.. Summary cladogram based on Fig. 2.
Species formerly classified as Weingartia, Sulcorebutia and Cintia showed a close relationship to each other and to species of Rebutia with naked pericarpels (Rebutia II above), including the type species R. minuscula. The larger group of species of Rebutia studied, those with hairy or bristly pericarpels, formed a separate, more distantly related clade (Rebutia I). It was suggested that these be excluded from the genus, and , Plants of the World Online placed them in the genus Aylostera.
Species The number of species has been debated, because of disagreement both over what constitutes the genus and what constitutes a species. A very large number of plants that have circulated as species of Rebutia are now generally regarded as varieties, forms or synonyms of others.Cf. the list of approximately two hundred names under Rebutia (not to mention those given under other genera) provided in B. Fearn and L. Pearcy, The Genus Rebutia, 1895-1981, Matlock: Abbey Brook, 1981, pp.60-71. E. F. Anderson recognised 41 species in 2001.Edward F. Anderson, The Cactus Family, Portland, Oregon: Timber Press, 2001, pp.599-611. Only the following three species were accepted by Plants of the World Online . Image Scientific name Distribution Rebutia fabrisii Rausch Argentina Rebutia minuscula K.Schum. Argentina Rebutia padcayensis Rausch Bolivia to Argentina (Salta)
Gallery
Notes and references
External links
Rebutia — Names and Identification Cactiguide.com: Rebutia