Taxonomic studies on the genus Crassula L

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dc.contributor.advisorSchelpe, E A C L Een_ZA
dc.contributor.authorTolken, H Ren_ZA
dc.date.accessioned2016-03-17T07:18:14Z
dc.date.available2016-03-17T07:18:14Z
dc.date.issued1974en_ZA
dc.description.abstractThe difficulties involved in the taxonomy of the genus Crassula, such as the extensive variation and often difficult species complexes, vicariousness and hybridization, are sketched against a historical background. These difficulties have prompted the author to review concepts of taxa from subspecific to generic level and have also led to the approach adopted in this work. It is argued that in several genera and sections, as previously recognized, too much stress was placed on the several floral characters which form part of a pollination syndrome which is shown up by convergent developments of these flower types. The different types of seedling morphology recognized are considered in relation to the morphology of adult plants and their affinities at specific and sectional level. The distribution of the hydathodes has proved useful in the delimitation of supra-specific taxau ThB morphology of the developing seedlings and the distribution of the hydathodes on the leaves become the main arguments for a new classification in the genus Crassula. A cytological review stresses the different basic chromosome numbers (8,7) and their structural differences for the delimitation of the subgenera. Problems in determining the original basic number and the high percentage of polyploidy with various rainfall conditions are evaluated. Subsequently the characteristics and affinities of Crassula and its subgeneric taxa are briefly discussed. The key to the species, subspecies and varieties is divided into twelve groups which are similar to sections or groups of sections recognized. Within the genus Crassula 2 supgenera, 21 sections, 11 subsections and 144 Southern African species with 124 subspecific taxa are distinguished, described, their variation recorded and their diagnostic features accentuated. Species insufficiently known and excluded are briefly discussed.en_ZA
dc.identifier.apacitationTolken, H. R. (1974). <i>Taxonomic studies on the genus Crassula L</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Biological Sciences. Retrieved from http://hdl.handle.net/11427/17898en_ZA
dc.identifier.chicagocitationTolken, H R. <i>"Taxonomic studies on the genus Crassula L."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 1974. http://hdl.handle.net/11427/17898en_ZA
dc.identifier.citationTolken, H. 1974. Taxonomic studies on the genus Crassula L. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Tolken, H R AB - The difficulties involved in the taxonomy of the genus Crassula, such as the extensive variation and often difficult species complexes, vicariousness and hybridization, are sketched against a historical background. These difficulties have prompted the author to review concepts of taxa from subspecific to generic level and have also led to the approach adopted in this work. It is argued that in several genera and sections, as previously recognized, too much stress was placed on the several floral characters which form part of a pollination syndrome which is shown up by convergent developments of these flower types. The different types of seedling morphology recognized are considered in relation to the morphology of adult plants and their affinities at specific and sectional level. The distribution of the hydathodes has proved useful in the delimitation of supra-specific taxau ThB morphology of the developing seedlings and the distribution of the hydathodes on the leaves become the main arguments for a new classification in the genus Crassula. A cytological review stresses the different basic chromosome numbers (8,7) and their structural differences for the delimitation of the subgenera. Problems in determining the original basic number and the high percentage of polyploidy with various rainfall conditions are evaluated. Subsequently the characteristics and affinities of Crassula and its subgeneric taxa are briefly discussed. The key to the species, subspecies and varieties is divided into twelve groups which are similar to sections or groups of sections recognized. Within the genus Crassula 2 supgenera, 21 sections, 11 subsections and 144 Southern African species with 124 subspecific taxa are distinguished, described, their variation recorded and their diagnostic features accentuated. Species insufficiently known and excluded are briefly discussed. DA - 1974 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1974 T1 - Taxonomic studies on the genus Crassula L TI - Taxonomic studies on the genus Crassula L UR - http://hdl.handle.net/11427/17898 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/17898
dc.identifier.vancouvercitationTolken HR. Taxonomic studies on the genus Crassula L. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 1974 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/17898en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Biological Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherBotanyen_ZA
dc.titleTaxonomic studies on the genus Crassula Len_ZA
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnamePhDen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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