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Twenty nothogeneric names, some of them new, cover the known cases of spontaneous intergeneric hybrids in Cactaceae. They can be grouped into 5 comparia in geographically distinct areas, some sharing the same pollinator, others with up to 4 different pollen vectors probably involved. Possible origins by cross-pollination, and the evolutionary significance of wide crossing are briefly discussed.
25 paintings of cacti from the Tomer Collection at the Hunt Institute are published for the first time, along with modem names and annotations. A brief summary is added, drawn from the works of Rickett and McVaugh, of the Sessé and Mociño expedition of 1787–1803, the subsequent fate of the findings, the rediscovery of the lost plates and their importance to cactus taxonomy today.
A new dwarf species of Ornithogalum is described as O. sardienii van Jaarsveld from the Oudtshoom region of the Little Karoo, S. Africa. Its systematic position, distinctions from allied species and ecology are discussed.
Among 74 Eurasian species of Sedum, Rhodiola, and Hylotelephium 10 different combinations of life-forms and growth-forms can be distinguished. The anatomy of the shoots and roots in combination with the patterns of secondary growth, especially of the wood, indicate that these life-forms and growth-forms all have evolved from an ancestral perennating form with unspecialised, suberect or prostrate, rooting, leafy shoots and a hapaxanth flowering shoot. The habit of this ancestral form is similar to Sedum acre, and, moreover, is still quite abundant in Sedum. More advanced life-forms, growth-forms and secondary growth patterns have often evolved independently in different infrageneric groups of Sedum as well as in different genera of Sedoideae, and systematically these features are of little value.
The genus Piaranthus R. Br. comprises a group of small-stemmed, mat-forming stapeliads occurring in the Cape Province of South Africa and in southern Namibia. Here, they typically can be found under shrubs in karroid vegetation.
Living plants in habitat as well as in cultivation and herbarium material were used in this monograph to study the character state and biology of the closely related species. The comparative morphological analysis of vegetative and generative organs, combined with data from an investigation of floral flavonoids, from a breeding programme and from field studies, form the basis for the new taxonomic approach presented. Of the 16 species formerly recognized, only P. comptus, P. decorus, P. geminatus, P. parvulus, P. framesii and P. punctatus are accepted, supplemented by a new species from the southwestern Cape, P. barrydalensis. Additionally two new combinations are made: P. decorus subsp. cornutus and P. geminatus var. foetidus.
A new species of Haworthia from near Adelaide in the Eastern Cape is described as H. pringlei. Its closest ally is H. xiphiophylla, and the points of difference are noted. Not more than 80 specimens remain in the only known population in habitat.
Five genera of Portulacaceae are reviewed and reduced to three, one of which (Avonia) is new. Grahamia is expanded to include Talinaria, Talinopsis and Xenia and two species previously included in Anacampseros from Australia and Argentina. Collectively these form the new Tribe Anacampseroteae. Greater emphasis on vegetative characters produces a classification recognising three dissimilar life forms and harmonising better with the geographical spread of the 29 species involved.