| Presented here as separate chapters are two investigations relevant to the systematics of Lauraceae. In Chapter One, phylogenetic relationships among 122 species of Lauraceae representing 44 of the 55 currently recognized genera are inferred from sequence variation in the chloroplast and nuclear genomes. The trnL-trnF, trnT- trnL, psbA-trnH, and rpl 16 regions of cpDNA, and the 5′ end of 26S rDNA resolved major lineages, while the ITS/5.8S region of rDNA resolved a large terminal clade. The phylogenetic estimate is used to assess morphology-based views of relationships and, with a temporal dimension added, to reconstruct the biogeographic history of the family. Results suggest Lauraceae radiated when trans-Tethyean migration was relatively easy, and basal lineages are established on either Gondwanan or Laurasian terrains by the Late Cretaceous. Most genera with Gondwanan histories place in Cryptocaryeae, but a small group of South American genera, the Chlorocardium-Mezilaurus clade, represent a separate Gondwanan lineage. Caryodaphnopsis and Neocinnamomum may be the only extant representatives of the ancient Lauraceae flora documented in Mid- to Late Cretaceous Laurasian strata. Remaining genera place in a terminal Perseeae-Laureae clade that radiated in Early Eocene Laurasia. Therein, non-cupulate genera associate as the Persea group, and cupuliferous genera sort to Laureae of most classifications or Cinnamomeae sensu Kostermans. Laureae are Laurasian relicts in Asia. The Persea group and Cinnamomum group (of Cinnamomeae) show tropical amphi-Pacific disjunctions here credited to disruption of boreotropical ranges by Eocene-Oligocene climatic cooling. The Ocotea complex accommodates remaining Cinnamomeae and shows a trans-Atlantic disjunction possibly derived from a Madrean-Tethyan ancestral distribution. These findings support Laurasian ancestry for most extant Lauraceae, with their considerable neotropical representation primarily derived from Early Miocene radiation of the Ocotea complex upon reaching South America.; In Chapter Two, the taxonomy of Endlicheria, a South America-centered genus of the Ocotea complex, is updated in monographic custom, and with the benefit of additional molecular data showing that its members are nested within Rhodostemonodaphne and Ocotea, its delimitation is assessed in morphological detail. Sixty species of Endlicheria are recognized, of which 16 are newly described. Nine infra-generic species groups are informally recognized. Of these, the Endlicheria punctulata species group is closer to species of the Ocotea cernua species group than to congeners, in both molecular and morphological aspects. Representatives of each of the eight remaining species groups are united with a diverse representation of Rhodostemonodaphne in a well supported but unresolved clade. The significance of this Endlicheria-Rhodostemonodaphne alliance is explored from a morphological perspective. |
