|Rebutia minuscula var. wessneriana|
Rebutia is a genus in the family Cactaceae, native to Bolivia and Argentina. They 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.
The limits of the genus are currently uncertain – in particular whether or not it includes species formerly or currently placed in the genera Aylostera, Cintia, Sulcorebutia and Weingartia. The number of species included varies widely from source to source. 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.
The genus was designated in 1895 by Karl Moritz Schumann and named after Pierre Rebut (1828–1898), a French cactus nurseryman. The type species is R. minuscula, which has been in cultivation since 1887.
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 Saccardo 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|
|C. Backeberg||Donald||ICSG Anderson||Rowley||Mosti & Papini|
|Rebutia K. Schum.||Rebutia
The variation in the treatment of the genus is illustrated by the difference between Mosti et al., who in 2011 treated Aylostera and Weingartia (including Cintia and Sulcorebutia) as distinct from Rebutia, and the Plant List, which as of March 2013[update] separated Cintia, Sulcorebutia and Weingartia from Rebutia, but merged Aylostera.
The number of species is similarly debatable, 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. E. F. Anderson recognised forty-one species in 2001. As of March 2013[update], the Plant List accepted only 12 species, along with a much larger number of synonyms and unresolved names:
- Rebutia albopectinata Rausch (synonym Aylostera)
- Rebutia atrovirens (Backeb.) Sida (synonym Mediolobivia)
- Rebutia deminuta (F.A.C. Weber) Britton & Rose (synonym Aylostera)
- Rebutia fidaiana (Backeb.) D.R. Hunt (synonym Weingartia)
- Rebutia fiebrigii (Gürke) Britton & Rose (syn. R. fabrisii Rausch) (synonym Aylostera)
- Rebutia heliosa Rausch (synonym Aylostera)
- Rebutia langeri (J. Falkenberg & K. Neumann) G. Navarro (synonym Sulcorebutia)
- Rebutia margarethae Rausch (syn. R. padcayensis Rausch)
- Rebutia marsoneri Werderm.
- Rebutia minuscula K.Schum. (syns R. chrysacantha Backeb., R. senilis Small, R. violaciflora Backeb., R. wessneriana Brewer.)
- Rebutia pulvinosa F. Ritter & Buining (synonym Aylostera)
- Rebutia ritteri (Wessner) Buining & Donald (synonym Mediolobivia)
Recent research has indicated that the genus Rebutia as currently defined is polyphyletic. Sulcorebutia and Weingartia were kept as separate genera in the study; a summary cladogram for those species studied is shown below.
Species formerly classified as Weingartia, Sulcorebutia and Cintia show a close relationship to each other and to species of Rebutia with naked pericarpels (Rebutia II), including the type species R. minuscula. The larger group of species of Rebutia studied, those with hairy or bristly pericarpels, form a separate, more distantly related clade (Rebutia I). It is suggested that these be excluded from the genus.
Rebutia I - Aylostera, Mediolobivia
Notes and references
- Monatsschrift für Kakteenkunde, 5: 102, 1895
- N. L. Britton, J. N. Rose, The Cactaceae, Washington, 1920, vol.III, p.45.
- "List of genera in family Cactaceae", Vascular Plant Families and Genera (Royal Botanic Gardens, Kew), retrieved 2013-03-10
- Mosti, Stefano; Bandara, Nadeesha Lewke & Papini, Alessio (2011), "Further insights and new combinations in Aylostera (Cactaceae) based on molecular and morphological data", Pakistan Journal of Botany 43 (6): 2769–2785, retrieved 2013-03-19
- "Search results for Aylostera, Cintia, Sulcorebutia and Weingartia", The Plant List
- 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.
- Edward F. Anderson, The Cactus Family, Portland, Oregon: Timber Press, 2001, pp.599-611.
- "Search results for Rebutia", The Plant List, retrieved 2013-03-19
- Ritz, Christiane M.; Martins, Ludwig; Mecklenburg, Rainer; Goremykin, Vadim & Hellwig, Frank H. (2007), "The molecular phylogeny of Rebutia (Cactaceae) and its allies demonstrates the influence of paleogeography on the evolution of South American mountain cacti", American Journal of Botany 94: 1321–1332. Summary cladogram based on Fig. 2.
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