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Abstract

Towards a Natural Classification of Plantago - Chemical and Molecular Systematics

Nina Rønsted

 

Plantago (Plantain; dansk vejbred; family Plantaginaceae) consists of over 200 annual and perennial herbs and semishrubs with an impressive world-wide distribution. Plantago is considered monophyletic and recent molecular phylogenetic studies suggest a close relationship with a number of genera from Scrophulariaceae s.l.. In a Danish morphological phylogenetic classification of Plantago from 1996, six subgenera and a number of sections and series are recognised. The present work use plant secondary metabolites (iridoid glucosides and caffeic acid derivatives) and DNA sequence data of roughly 60 species to evaluate the infra-generic classification of Plantago. The results of the chemical and molecular studies are generally in accordance with the morphological classification, but subgenus Albicans is paraphyletic to subgenus Psyllium. Iridoid glucosides are shown to be valuable taxonomic markers of subgenera and sections. The molecular variation within the genus is high, which was not expected from the relatively stereotyped morphology. Molecular clock calibrations indicate a recent origin, in the light of which Plantago must have been incredibly successful in speciating and dispersing to new sites.

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