What is Seseli diffusum? A comparative morphological and molecular appraisal of a critical species of the Umbelliferae.

A comprehensive study of critical South Asian species Seseli diffusum (Umbelliferae—Apioideae—Apieae) was carried out to determine the most suitable taxonomic position of the species, based on morphology (carpoanatomy, micromorphology of the fruit indumentum and some vegetative characters) and molecular data from nrDNA ITS region sequencing. Comparison with certain other species of Seseli and several provisionally related Apieae genera showed a close affinity of S. diffusum to the genus Psammogeton and more distant relationships with some species of Trachyspermum, clearly polyphyletic genus. No species of Seseli, even in broad sense, was found to be closely related to S. diffusum. It was proposed to transfer this species into Psammogeton, while separating a new section, Pseudoseseli, within the latter. [ABSTRACT FROM AUTHOR]