科研之友
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摘要
The tribe Platycarpheae has three species; they are found from South Africa, to Namibia and Botswana. The three species have traditionally been placed in a single genus but were recently divided into two (Platycarpha and Platycarphella). All have 'secondary heads' formed by tightly clustered heads on the crown of the rhizome. The three species are easily separated from one another based on characters such as leaf type, head size, style and corolla length, and pollen type. Morphological and molecular data support Platycarpheae as a monophyletic group within the subfamily Cichorioideae but no firm sister-group relationship has been determined. The three species form a monophyletic group on a long branch: Platycarphella carlinoides and Platycarphella parvifolia share more characters and are sister-taxa; Platycarpha glomerata has the largest number of unique features and is the sister taxon to the other two species. The distributions and flowering times of the three species are different. Platycarphella carlinoides is the most widespread of the species and grows in northwestern South Africa, the central highlands of Namibia, and southwestern Botswana; its peak flowering time is March-July. Platycarphella parvifolia is found in north central to northeast South Africa and flowers mostly in August to October, and Platycarpha glomerate is from inland eastern South Africa and usually flowers from November to early February. The biogeographic pattern is consistent with one of a widespread ancestral species that became fragmented by the rise of the Great Escarpment and climate change.
- 出版日期2011-3
