Systematics/Phytogeography / Taxonomie/ Section
NŁrk, Nicolai M. , Blattner, Frank R. .
A cladistic analysis of Hypericum (Hypericaceae) based on morphological characters.
The genus Hypericum L. (St. Johnís Wort) consists of >440 species of small trees, shrubs and herbs, distributed mainly in temperate regions of the Northern Hemisphere and tropical high elevation habitats. It is one of the 100 largest angiosperm genera and one of the few where the alpha taxonomy is nearly completed. Within the genus either 36 or 32 sections are currently recognized, as defined by floral and vegetative morphology.
The monographer of the genus, N. Robson, proposed a genealogical scheme of putative relationships and postulated evolutionary trends in Hypericum. However, no formal cladistic analysis of the entire genus was conducted up to now to circumscribe monophyletic groups within Hypericum.
To revise hypotheses of character evolution and to test monophyly of the sections, a cladistic analysis was conducted based on Robsonís alpha taxonomic diagnoses. Ninety-five characters were considered to be phylogenetically informative, and were coded for 356 ingroup species and 8 outgroup taxa, representing eight of the nine genera of Hypericaceae. Parsimony analyses were performed and the obtained tree indicates that: 1) Hypericum is monophyletic, if the two monotypic genera Lianthus and Santomasia are included. 2) The sistergroup of Hypericum is Triadenum, and 3) three major groups within Hypericum can be described: (i) a basal grade containing Old World sections described as primitive by Robson, as well as the monophyletic New World section Myriandra. (ii) A clade containing section Hypericum was not in full agreement with Robsonís classification, as it contains also the members of section Adenosepalum. (iii) A clade with mainly New World species representing sections Brathys and Trigynobrathys.
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1 - Institute of Plant Genetics and Crop Research (IPK), Taxonomy & Evol. Biology, Gatersleben, D-06466, Germany
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM