Genera Of Commelinaceae Research Articles

A third species of Polyspatha, an endemic African genus of Commelinaceae

Polyspatha oligospatha Faden, the third species in a small African endemic genus of Commelinaceae, is described. It is widespread but has been overlooked because of its small stature and resemblance to small plants of Polyspatha paniculata. It differs from both Polyspatha paniculata and Polyspatha hirsuta, the two other species, by its leaf pubescence, fewer, more widely spaced and usually patent spathes, deeply ridged seeds with numerous knobby, transversely interrupted ridges, and morning anthesis. It occurs throughout the Congolian forests from Cameroon to Uganda, but it is also disjunct in Ivory Coast, across the Dahomey gap.

Chromosomes of four species in three genera of Commelinaceae from China and their systematic implications

Chromosomes of four species in three genera of Commelinaceae from China were examined. Spatholirion longifolium had 2n = 20. This small genus is considered to be of a possible polyploid origin based on x = 5, a basic number shared by its closest ally, the monospecific genus Streptolirion, with its only species having 2n = 10. The two genera were found to be very different from each other in their karyotypic constitution. The differences in both chromosome number (2n = 20 vs. 10) and karyotypic constitution support their separation as two independent genera. The remaining three species, Amischotolype hispida, Porandra ramosa and P. scandens, all had 2n = 36. In view of the occasional occurrence of 2n = 18 in the African Coleotrype, a genus very close to Amischotolype and Porandra in gross morphology, these three species are all very probably polyploid based on x = 9. The high degree of karyotypic similarity of the three genera also strongly indicates their close affinity and supports their placement in the subtribe Coleotrypinae. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society, 2006, 152, 399–403.

The genera of Commelinaceae in the southeastern United States

The genera of Commelinaceae in the southeastern United States

Phytogeography of African Commelinaceae

Africa (including Madagascar) has nearly twice as many species of Commelinaceae as any other continent (approximately 270 species, or about 40% of the total in the family). Of the 17 genera which are native, seven (Anthericopsis, Coleotrype, Palisota, Polyspatha, Pseudoparis, Stanfieldiella and Triceratella) are endemic, the highest percentage generic endemism of any continent. Within Africa gcneric diversity is slightly higher in western than in eastern tropical floras. Species richness, however, is greatest in eastern Africa, mainly due to a high diversity of species of Commelina and Aneilema. Africa shares more genera with Asia (nine) than with any other continent. Only one African genus, Buforrestia, is neither endemic nor shared with Asia. Its western African/northeastern South American distribution is unique in the family. Besides Buforrestia, only five other genera of Commelinaceae (out of a total of 50 in the family), occur in both the Old and New Worlds. These genera. Aneilema, Commelina, Floscopa, Murdannia and Pollia are all very widespread in the Old World, occurring in Australia and Asia in addition to Africa (both continental and Madagascar). Madagascar is relatively poor in species (31). but these include the endemic Madagascan genus Pseudoparis, the sole African species of Rhopalephora, and the largest number of species of the Afro-Malagasy endemic genus Coleotrype. The high rate of generic endemism of Commelinaceae in Africa probably indicates that Africa was one of the ancient centres of diversity for the family. The high species diversity is more likely due to relatively recent radiations by genera pre-adapted to survival in non-forest habitats. The occurrence of only a small number of genera on both sides of the Atlantic suggests that the Commelinaceae have been evolving independently in the eastern and western hemispheres for a long period.

Aetheolirion, a New Genus of Commelinaceae from Thailand, with Notes on Allied Genera

During a recent visit to Kew, Mr. Kai Larsen, of the Danmarks Farmaceutiske Hojskole, Copenhagen, was examining a mixed collection of unnamed monocotyledons from Thailand when he came across five collections of an extraordinary plant collected by A. F. G. Kerr, Put and Winit during the period 1922-1929. Mr. Larsen recognised that the plant showed some similarities to Streptolirion Edgew. and Spatholirion Ridley in its leaves, bracts and inflorescences, but the linear fruits up to 16 cm. long containing winged seeds resembled nothing known in the Commelinaceae. Together with some other interesting finds, Mr. Larsen kindly drew my attention to these specimens as deserving further study. A full examination of this plant shows that it indeed has affinities with Streptolirion and Spatholirion, but also that it differs in important respects from these genera in the androecium, which in some classifications of the family serve to distinguish tribes or even subfamilies. The plant was finally considered to represent a new genus.