The genus Iliamna Greene has a taxonomically complex history. Since its desciption in 1906, the genus was not recognized for some time, several species were initially placed into other genera, and the species status of a few was questioned. Today, eight species of Iliamna are recognized. Six species are located in western North America and two are found isolated to the east. Species in Iliamna are very similar morphologically with only a few characters distinguishing several as separate entities. The need for systematic study became apparent since all but one species are considered rare or endangered. Also, the differentiation between two endangered species, I. corei and I. remota, was unclear in a previous study using random amplified polymorphic DNA fragments. Of the western species, four overlap in distribution (I. crandallii, I grandi ora, I. longisepala, and I. rivularis) and their recognition as separate species has been questioned. The focus of this study was to develop a phylogeny for Iliamna using sequences from the internal transcribed spacer region (ITS) of the nuclear ribosomal RNA genes in order to determine its biogeographical and evolutionary history. Cladistic analysis was performed and the resulting phylogeny is presented. The ITS data provide new insights in the origination of the genus and its distribution. In Iliamna, the ITS region is 677 base pairs long with 120 sites providing information in the formation of phylogenetic trees. Iliamna forms a well-supported clade distinct from related genera and is monophyletic. Three well-supported groups are formed. One contains representatives from the Pacific Northwest. Another contains all of the remaining species with the third clade nested therein. This last clade contains the two eastern species, I. corei and I. remota, but there is not enough variability to support the divergence of these taxa as distinct species. There is also not sufficient variability in the ITS region to identify the western species I. crandallii, I. grandi ora, I. longisepala and I. rivularis as distinct entities. / Master of Science

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 79-91).

Thesis (M.S.)--University of Georgia, 2001. / Includes bibliographical references (leaves 74-78). Also available in electronic format via Internet.

Beginning in the late 1930s, fire exclusion has drastically altered the vegetation dynamics of the southern Appalachian Mountains. Extremely low fire frequency has allowed for more shade-tolerant species to invade once predominantly open forests and has made it almost impossible for fire-dependent species to establish on a site. One such species is the endangered Peters Mountain mallow (Iliamna corei Sherff.) located on Peters Mountain in The Nature Conservancy s Narrows Preserve in Giles County, Virginia. This paper focuses on the fire history and stand dynamics of Peters Mountain and how fire exclusion has altered the forest composition. The historic fire frequency and successional changes discovered here may provide an insight into management strategies for the mallow. Seventy-nine fire scarred cross-sections were taken and aged to determine fire history dates and frequencies. Three 50x20 meter plots were set up on opposing aspects: northwest and southeast. The aspects were chosen at the direction of The Nature Conservancy personnel. All trees within were identified, cored and aged to determine species composition and the establishment dates of all trees. Fire history analysis revealed a mean fire interval of 2.48 years, a Weibull median fire interval of 2.18 years and a 25 percent scarred class mean fire interval of 12.5 years. Stand dynamic results show that Quercus montana has established on Peters Mountain prior to fire exclusion and remains the dominate species on the landscape. An increased number of fire intolerant species (including Acer rubrum, Sassfras albidum, Nyssa sylvatica) have been establishing on Peters Mountain during the decades of decreased fire frequency, suggesting a shift in forest composition. Frequent fires are suggested for mallow management and oak forest maintenance.

The Malacothamnus alliance consists of three genera, Iliamna, Malacothamnus, and Phymosia. The genera are considered taxonomically complex since hybridization freely occurs, polyploidy levels vary, and there is a lack of distinct morphological characters to delineate taxa. Several taxonomic treatments have been prepared for each genus, but relationships within the genera and the relationship of the Malacothamnus alliance to others in the Malvaceae remains unknown. This multifaceted study aimed to (a) examine the monophyly of the Malacothamnus alliance and its position in the Malvaceae, (b) determine the relationships between genera in the alliance, (c) compare variation of nuclear and chloroplast genes in the alliance, (d) prepare revised taxonomic treatments for Iliamna and Malacothamnus, and (e) examine the probability of successful hybridization in Iliamna. The monophyly of the Malacothamnus alliance was not confirmed using DNA sequences of both nuclear and chloroplast regions. In Iliamna, little sequence variation was detected among taxa in the Rocky Mountains; however, the nuclear and chloroplast regions conflicted with regard to the relationships of the western and eastern taxa. An ancestral copy of the chloroplast genome is shared between the two eastern U.S. Iliamna species and Phymosia (Bahamas and Mexico). The nuclear ITS sequences indicated the western U.S. Iliamna species were more closely related to Phymosia and Malacothamnus than to other species in Iliamna. Neither data set provided sufficient variation to resolve relationships of species in Malacothamnus. Genetic variation and the feasibility of hybridization in Iliamna supported the results of the broader phylogenetic studies. Iliamna corei and I. remota are recently derived from I. rivularis. Hybrid offspring of I. corei and I. remota had higher viability and fecundity than did hybrids between crosses of either species and I. rivularis. The Virginia populations of I. corei and I. remota are more genetically similar than either is to Illinois populations of I. remota. However, the species are morphologically distinct and can easily be distinguished from others in the genus. Revised taxonomic treatments for Iliamna and Malacothamnus based on surveys of herbarium material are presented. Taxonomic revisions include the new combinations of Iliamna grandiflora subsp. grandiflora and I. grandiflora supsp. crandallii and the resurrection of Malacothamnus hallii and M. orbiculatus. / Ph. D.