A monographic study of Lygodium Swartz (Pteridophyta: Lygodiaceae).
Item
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Title
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A monographic study of Lygodium Swartz (Pteridophyta: Lygodiaceae).
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Identifier
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AAI9908323
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identifier
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9908323
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Creator
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Hanks, Judith Garrison.
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Contributor
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Adviser: John T. Mickel
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Date
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1998
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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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A monographic study of the pantropical fern genus Lygodium has been undertaken, based on the gross morphological comparisons of approximately five thousand herbarium specimens and on phytochemical analysis and spore architecture. The biogeography and ecology, paleobotany, cytology, and gametophyte morphology are summarized. Interspecifically the genus is homogeneous, and yet, intraspecifically it is polymorphic. To resolve some of the problems created by this inherent variability, phytochemical, spore, and sporophyte characters were included in a cladistic analysis to reflect species relationships.;Twenty-six species of Lygodium are treated along with three hybrids. The taxonomic treatment includes a review of the nomenclature and a key to the species. General morphological features found to be most consistent in Lygodium are type of branching pattern, size of pinna-stalk, articulation, pulvini, margin pattern, venation pattern and degree of dimorphism. Characteristics that are most variable are indument amount, segment shape and size, and size of sorophores.;The phytochemical analysis resulted in the isolation of twenty-two hydroxycinnamic acid conjugates from L. japonicum. A methodology for the extraction, purification, and preliminary identification of these compounds has been developed. The compounds elucidated, thus far, are {dollar}\beta{dollar}-1-O-caffeoylglucose, 4-O-(E)-caffeoylglucose, 4-O-p-coumaroyl glucose, and an as yet unnamed compound that is new to natural product chemistry. The co-occurrences of these compounds in other species of Lygodium were then analyzed to determine the importance of these chemicals in the taxonomy and phylogeny of Lygodium.;Spore morphology studies indicate that the overall pattern is constant intraspecifically and a very useful character in species identification. The spore architecture revealed four basic surface patterns in Lygodium: tuberculate, ridged-verrucate, reticulate and granulate. All twenty-six species were surveyed resulting in a key based entirely on spore morphology.;The cladistic analysis included 42 characters with 111 states. Lygodium flexuosum, L. japonicum, L. kerstenii and L. venusum represent the most ancestral clade. The rest of the taxa are divided into two monophyletic groups with L. polystachyum as the intermediate species between them and the ancestral group. Based on outgroup analysis the following are considered pleisiomorphic in Lygodium: short-branching rhizome, pinnate branching pattern, pubescence, entire segments, and lack of articulation or pulvini.
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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.
