Thesis (M.S.)--Oregon State University, 1989. / Includes bibliographical references. Also available on the World Wide Web.

Inaugural dissertation (Ph. D.)--Königl. Christian-Albrechts-Universität zu Kiel. / Includes bibliographical references.

The potential for introgression in the British Senecio polyploid complex was investigated using numerical taxonomic methods. It has been suggested that introgression of the introduced Mediterranean diploid S. squalidus L. into the native British tetraploid species S. vulgaris var. vulgaris (non-radiate) has given rise to the inland radiate morph S. vulgaris var. hibernicus Syme. The research reported in this thesis falls into three main sections. The first part describes the results of a crossing program to determine the interfertility relationships of the British Senecio species, S. vulgaris var. vulgaris, vulgaris var. hibernicus, S. vulgaris var. denticulatus, S. viscosus, S. squalidus, S. vernalis, and S. cambrensis. Interspecific hybrids at the diploid, triploid and tetraploid levels were formed. If was found that hybrid fertility was largely dependent on genomic balance. The phenetic similarities of the interspecific hybrids and the parental species were examined by multivariate analysis of 64 morphological characters, using both cluster analysis and ordination methods. The results obtained suggest that radiate S. vulgaris may have arisen via non-reduction of a S. squalidus gamete. The backcross progeny of a tetraploid S. vulgaris var. vulgaris x S. sgualidus hybrid were phenetically close to radiate S. vulgaris. However, F2 progeny of naturally occurring triploid vulgaris x S. squalidus and S. x subnebrodensis hybrids were found to have chromosome numbers between the diploid and sub-triploid levels. The diploid F2 hybrids were morphologically indistinguishable from S. squalidus. The third part of the thesis describes the results of a morphometric analysis of the geographic variation in radiate and non-radiate S. vulgaris, and S. squalidus in central Scotland. It was found that the interpopulation differentiation in both radiate and non-radiate S. vulgaris was correlated with both the geographic distribution of radiate S. vulgaris and the longitude. In conclusion it is suggested that, although S. vulgaris var. hibernicus may have originated by introgression of S. squalidus into S. vulgaris var. vulgaris, the current potential for introgression would appear to be in other directions, from the tetraploids S. vulgaris and S. viscosus into the diploid S. squalidus. The greatest extent of gene flow, however, was found to be from radiate S. vulgaris into non-radiate S. vulqaris.

Spore morphology of Polypodiaceae and Grammitidaceae from Taiwan were studied with light microscope and scanning electron microscope. Totally 18 genera and 62 species were observed. Polypodiaceae spores are ellipsoidal and monolete except Loxogramme grammitoides; with spore ornamentation tuberculate, verrucate, echinate, globule, rugate, undulate, foveolate and/or vermiculate. Grammitidaceae spores are global, trilete with spore ornamentation granulate, tuberculate and/or globules. The spore surface ornamentation can be used as taxonomic characters in Polypodiaceae and Grammitidaceae at familial, genera and species levels. Based on spore characters, Polypodiaceae and Grammitidaceae can be differentiated, Loxogrammeae and Drynariaeae are not separable from the rest of Polypodiaceae, and the current classification system of Lepisorieae and Microsoreae are not .internal consistent.

A polypodiaceous fern, Drynaria callispora sp. nov., is described from the upper Pliocene Sanying Formation in western Yunnan Province, southwestern China. This species with well-preserved pinnae and in situ spores is the first convincing Drynaria fossil record. Detailed morphological investigation reveals that D. callispora is characterized by 1) pinnatifid fronds with entire-margined pinnae having straight or zigzag secondary veins; 2) finer venation showing void quadrangular areoles, but occasionally with one unbranched veinlet; 3) one row of circular sori on each side of the strong primary vein; and 4) in situ spores with verrucate exospores elliptical in polar view and bean-shaped in equatorial view. A morphological comparison shows that D. callispora is significantly different from all the fossil species previously identified as drynarioids. A phylogenetic analysis of D. callispora supports that the fossil is closely related to D. sinica Diels and D. mollis Bedd., two extant species distributing in the Himalayas. The discovery of the new fern indicates that the genus Drynaria became diversified in its modern distribution region no later than the late Pliocene and had retained a similar ecology to that of many modern drynarioid ferns ever since.

As plantas que possuem hábito epifítico estão mais sujeitas as variações ambientais do que as de hábito terrestre, principalmente em relação à disponibilidade hídrica. A água, então, destaca-se como um dos fatores restritivos mais importantes. Entretanto, algumas espécies desenvolveram a capacidade de tolerar a dessecação, apresentando uma significante vantagem adaptativa na ocupação de habitats. O objetivo deste estudo foi verificar o grau e os mecanismos de tolerância à dessecação de quatro espécies de pteridófitas epifíticas que comumente co-ocorrem sobre mesmo forófito. Frondes expandidas e hidratadas foram coletadas para a quantificação e comparação do conteúdo relativo de água, integridade de membrana, pigmentos fotossintéticos, flavonóides, fenóis, açúcares solúveis e fluorescência da clorofila ao longo dos processos de dessecação e re-hidratação. Estas avaliações fisiológicas nos permitiram inferir que as espécies com características de tolerância à dessecação apresentam mais adaptações fisiológicas durante períodos de dessecação e rehidratação do que àquelas que não apresentam este comportamento. Os resultados obtidos também revelaram a existência de diferentes graus de tolerância nas três espécies consideradas tolerantes à dessecação. Polypodium polypodioides var. minimum foi a mais tolerante, seguida de Pleopletis pleopeltifolia e Polypodium hirsutissimum. Enquanto Microgramma squamulosa demonstrou evitar à dessecação. Assim, concluímos que estas espécies apresentam diferentes estratégias ecofisiológicas em relação ao estresse hídrico, minimizando possíveis danos irreversíveis às membranas celulares. Desta forma, otimizam a captura de luz durante períodos de re-hidratação, diminuem a competição inter-específica e facilitam a co-ocorrência destas quatro espécies. / Epiphytic plants are more sensible to environmental variations than terrestrial plants, especially in relation to water availability. The water then stands out as one of the most important limiting factors. However, some species have evolved the ability to tolerate desiccation, showing a significant adaptive advantage in the occupation of habitats. The aim of this study was to determine the degree and mechanisms of drought tolerance of four species of epiphytic ferns that commonly co-occur on the same host tree. Expanded and hydrated fronds were collected for quantification and comparison the relative water content, membrane integrity, photosynthetic pigments, flavonoids, phenols, soluble sugars and chlorophyll fluorescence over the processes of desiccation and rehydration. The results of the present study allowed us to infer that the tolerant species have more physiological adaptations during periods of desiccation and rehydration. Thus, tolerant species showed distinct degrees of tolerance: Polypodium polypodioides var. minimum was the most tolerant, followed by Pleopletis pleopeltifolia and Polypodium hirsutissimum. While Microgramma squamulosa shown avoidance desiccation. We conclude that these species exhibit different ecophysiological strategies in relation to water stress, minimizing possible irreversible damage to cell membranes. Thus optimize capture of light during periods of rehydration, reduce inter-specific competition and facilitating the co-occurrence of these four species.

As plantas que possuem hábito epifítico estão mais sujeitas as variações ambientais do que as de hábito terrestre, principalmente em relação à disponibilidade hídrica. A água, então, destaca-se como um dos fatores restritivos mais importantes. Entretanto, algumas espécies desenvolveram a capacidade de tolerar a dessecação, apresentando uma significante vantagem adaptativa na ocupação de habitats. O objetivo deste estudo foi verificar o grau e os mecanismos de tolerância à dessecação de quatro espécies de pteridófitas epifíticas que comumente co-ocorrem sobre mesmo forófito. Frondes expandidas e hidratadas foram coletadas para a quantificação e comparação do conteúdo relativo de água, integridade de membrana, pigmentos fotossintéticos, flavonóides, fenóis, açúcares solúveis e fluorescência da clorofila ao longo dos processos de dessecação e re-hidratação. Estas avaliações fisiológicas nos permitiram inferir que as espécies com características de tolerância à dessecação apresentam mais adaptações fisiológicas durante períodos de dessecação e rehidratação do que àquelas que não apresentam este comportamento. Os resultados obtidos também revelaram a existência de diferentes graus de tolerância nas três espécies consideradas tolerantes à dessecação. Polypodium polypodioides var. minimum foi a mais tolerante, seguida de Pleopletis pleopeltifolia e Polypodium hirsutissimum. Enquanto Microgramma squamulosa demonstrou evitar à dessecação. Assim, concluímos que estas espécies apresentam diferentes estratégias ecofisiológicas em relação ao estresse hídrico, minimizando possíveis danos irreversíveis às membranas celulares. Desta forma, otimizam a captura de luz durante períodos de re-hidratação, diminuem a competição inter-específica e facilitam a co-ocorrência destas quatro espécies. / Epiphytic plants are more sensible to environmental variations than terrestrial plants, especially in relation to water availability. The water then stands out as one of the most important limiting factors. However, some species have evolved the ability to tolerate desiccation, showing a significant adaptive advantage in the occupation of habitats. The aim of this study was to determine the degree and mechanisms of drought tolerance of four species of epiphytic ferns that commonly co-occur on the same host tree. Expanded and hydrated fronds were collected for quantification and comparison the relative water content, membrane integrity, photosynthetic pigments, flavonoids, phenols, soluble sugars and chlorophyll fluorescence over the processes of desiccation and rehydration. The results of the present study allowed us to infer that the tolerant species have more physiological adaptations during periods of desiccation and rehydration. Thus, tolerant species showed distinct degrees of tolerance: Polypodium polypodioides var. minimum was the most tolerant, followed by Pleopletis pleopeltifolia and Polypodium hirsutissimum. While Microgramma squamulosa shown avoidance desiccation. We conclude that these species exhibit different ecophysiological strategies in relation to water stress, minimizing possible irreversible damage to cell membranes. Thus optimize capture of light during periods of rehydration, reduce inter-specific competition and facilitating the co-occurrence of these four species.

As plantas que possuem hábito epifítico estão mais sujeitas as variações ambientais do que as de hábito terrestre, principalmente em relação à disponibilidade hídrica. A água, então, destaca-se como um dos fatores restritivos mais importantes. Entretanto, algumas espécies desenvolveram a capacidade de tolerar a dessecação, apresentando uma significante vantagem adaptativa na ocupação de habitats. O objetivo deste estudo foi verificar o grau e os mecanismos de tolerância à dessecação de quatro espécies de pteridófitas epifíticas que comumente co-ocorrem sobre mesmo forófito. Frondes expandidas e hidratadas foram coletadas para a quantificação e comparação do conteúdo relativo de água, integridade de membrana, pigmentos fotossintéticos, flavonóides, fenóis, açúcares solúveis e fluorescência da clorofila ao longo dos processos de dessecação e re-hidratação. Estas avaliações fisiológicas nos permitiram inferir que as espécies com características de tolerância à dessecação apresentam mais adaptações fisiológicas durante períodos de dessecação e rehidratação do que àquelas que não apresentam este comportamento. Os resultados obtidos também revelaram a existência de diferentes graus de tolerância nas três espécies consideradas tolerantes à dessecação. Polypodium polypodioides var. minimum foi a mais tolerante, seguida de Pleopletis pleopeltifolia e Polypodium hirsutissimum. Enquanto Microgramma squamulosa demonstrou evitar à dessecação. Assim, concluímos que estas espécies apresentam diferentes estratégias ecofisiológicas em relação ao estresse hídrico, minimizando possíveis danos irreversíveis às membranas celulares. Desta forma, otimizam a captura de luz durante períodos de re-hidratação, diminuem a competição inter-específica e facilitam a co-ocorrência destas quatro espécies. / Epiphytic plants are more sensible to environmental variations than terrestrial plants, especially in relation to water availability. The water then stands out as one of the most important limiting factors. However, some species have evolved the ability to tolerate desiccation, showing a significant adaptive advantage in the occupation of habitats. The aim of this study was to determine the degree and mechanisms of drought tolerance of four species of epiphytic ferns that commonly co-occur on the same host tree. Expanded and hydrated fronds were collected for quantification and comparison the relative water content, membrane integrity, photosynthetic pigments, flavonoids, phenols, soluble sugars and chlorophyll fluorescence over the processes of desiccation and rehydration. The results of the present study allowed us to infer that the tolerant species have more physiological adaptations during periods of desiccation and rehydration. Thus, tolerant species showed distinct degrees of tolerance: Polypodium polypodioides var. minimum was the most tolerant, followed by Pleopletis pleopeltifolia and Polypodium hirsutissimum. While Microgramma squamulosa shown avoidance desiccation. We conclude that these species exhibit different ecophysiological strategies in relation to water stress, minimizing possible irreversible damage to cell membranes. Thus optimize capture of light during periods of rehydration, reduce inter-specific competition and facilitating the co-occurrence of these four species.