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UBC Theses and Dissertations

Taxonomic study of Trillium ovatum forma hibbersonii O’Neill, Darlene, M.


The entity known as Trillium ovatum forma hibbersonii Taylor and Szczawinski was first discovered on the west coast of Vancouver Island in 1938 by JA. Hibberson (Holotype UBC 73131). Leonard Wiley invalidly published the taxon as Trillium hibbersonii in 1968. A review of the taxonomic status by T.M.C. Taylor and A.F. Szczawinski resulted in the publication of the taxon as Trillium ovatum forma hibbersonii (1975). The diagnosis stated this dwarf variant was part of the continuous series of intergradations of Trillium ovatum Pursh (Taylor and Szczawinski, 1975). Taylor and Szczawinski did not cite any small or intermediate samples that supported their conclusions. The present study was initiated to provide a comprehensive re-evaluation of the taxonomic status: separate species from Trillium ovatum; subspecies, variety or forma of Trillium ovatum? This study considers morphological differences, flavonoid analysis and Random Amplified Polymorphic DNA (RAPD), from natural populations and cultivated plants. I conclude that compelling evidence supports the raising of Trillium ovatum forma hibbersonii to specific status. Characteristics which support this conclusion are: 1) the limited geographical distribution of Trillium ovatum forma hibbersonii 2) different ecological niche and strong morphological divergence from Trillium ovatum 3) distinct dormancy/germination requirements 4) quantitative differences in the major flavonoid constituents of T. ovatum and T. ovatum forma hibbersonii

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