A SYSTEMATIC REVISION OF THE GENUS DIOSCOREA (DIOSCOREACEAE) IN THE INDIAN SUBCONTINENT (SRI LANKA).
Item
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Title
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A SYSTEMATIC REVISION OF THE GENUS DIOSCOREA (DIOSCOREACEAE) IN THE INDIAN SUBCONTINENT (SRI LANKA).
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Identifier
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AAI8409400
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identifier
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8409400
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Creator
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JAYASURIYA, ANTHONY HAROLD MAGDON.
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Contributor
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Tetsuo Koyama
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Date
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1984
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Botany
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Abstract
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The genus Dioscorea (sensu stricto) includes all true yams and is very widespread and diversified. Organography of the genus is discussed with emphasis on the taxonomic use of morphological variation within the genus. Information available on chemistry is reviewed with special reference to the secondary chemical compounds and their use in taxonomy. Distribution of edible yams is discussed with a historical perspective. Systematics of 21 species in 6 sections of the genus are studied. One new species from Sri Lanka is described. Morphological, anatomical, and chemical features are used in taxonomy and the inter- and intra-populational variations are carefully considered in delimiting the species. The morphological variation in the tubers, and to some extent also in the bulbils, is heavily influenced by selection under cultivation. The taxonomic significance of these features is therefore minimized. Subgenera are not recognized, but the traditional sections are accepted with certain modifications. The separation of the sections Trieuphorostemon and Lasiophyton is strongly recommended as evidenced by their differences in morphology, anatomy, and chemistry. Unjustifiable taxonomic inflation of the genus by some workers is obvious and, therefore, some previously described species and many varieties must be reduced to synonomy. Keys are provided for sections and species within them. Ample correlation between vegetative and reproductive morphology is observed among these species, and these characters are liberally used in the keys. Furthermore, characters of both staminate and pistillate plants are generally used in these keys. For each taxon, the nomenclature has been critically examined, and all names are typified. Anatomy of the fruit in representative species of 5 sections is investigated. The results showed interesting differences, which are used to consolidate these sections. A Synopsis of the major classifications of the species in the Indian Subcontinent is presented.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Biology
