1. The taxonomic history and currently accepted classification of the family Asclepiadaceae is presented and discussed. The evolutionary relationship with nearest families, overall geographical distribution and a brief note on economic importance of asclepiads are provided in a general account of the family. 2. A complete taxonomic account of the family for the Flora of Bangladesh is prepared for the first time after a comprehensive survey of the existing taxa. 56 species and 4 varieties from 25 genera are recognized from the area. A dichotomous key to the genera, based on field characters, is provided, and suprageneric, infrageneric and infraspecific classifications are given. A nomenclatural and typification note is provided with a proposal for 16 lectotypes and 3 topotypes according to ICBN. A few nomenclatural changes in some species are made and a full attention is paid to synonymy which results in a number of reductions. Wallich's asclepiad material from Bangladesh held at K-W and other major herbaria have been examined critically, and an index has been prepared with nomenclatural notes and current taxonomic status. There are 7 species and 2 varieties recorded new to the flora of Bangladesh. 2 new varieties, <i>Gymnema acuminatum</i> var. <i>glabrum</i> and <i>Tylophora indica</i> var. <i>intermedia</i>, have been described from Bangladesh. Some investigations on pollinaria, seed morphology and leaf flavonoids have been done. A comparative account of the morphology of the pollinaria of 50 species from 25 genera is prepared with a dichotomous key for the <i>Flora of Bangladesh</i>. Seed morphology under SEM for 14 species from 11 genera provides diagnostic features which may prove useful for supra- and infra-generic classifications. Flavonoid distribution in asclepiads is not taxonomically useful at any level of the taxonomic hierarchy. 3. Two genera, <i>Calotropis</i> and <i>Pentasacme</i>, have been revised for the first time with notes on their taxonomic history, distribution, ecology and synonymy. 3 species of <i>Calotropis</i> and 4 in <i>Pentasacme</i> are recognized. <i>C. procera</i> ssp. <i>hamiltonii</i> (Wight) Ali is reduced to <i>C. procera</i> (Aiton) R. Br. Two sections in the genus <i>Pentasacme</i> are recognized: sect. <i>Pentasacme</i> and sect. <i>Wallichiana</i> (sect. nov.). <i>Pentasacme championii</i> Benth. is considered as a synonym of <i>P. caudatum</i> Wall. ex Wight.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:290235 |
| Date | January 1990 |
| Creators | Rahman, M. A. |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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