Diversity and taxonomy of the Trifolium lupinaster polymorphic complex in Eastern Europe and Asia

Abstract

The section Lupinaster of the genus Trifolium (Fabaceae) is characterized by taxonomic complexity due to the high level of polymorphism and polyploidy. Variants of T. baicalense, T. ciswolgense, T. pacificum, and T. spryginii are analyzed using morphological and molecular data to determine their taxonomic status. These species, which grow in Eastern Europe, Ural, Central and East Asia, and the Russian Far East, have been previously separated from T. lupinaster. ITS and trnL-trnF sequences show limited variation. All the investigated species of the T. lupinaster complex have identical ITS sequences, but slight differences due to single substitutions in the trnL-trnF region. The morphological variation of the leaflets and underground organs were characterized. According to these results, T. baicalense, T. ciswolgense, and T. spryginii, should be regarded as synonyms of T. lupinaster, whereas the Far Eastern T. lupinaster subsp. pacificum, distributed along the Pacific seashore of Eurasia (Russia and Japan), is considered as a subspecies of T. lupinaster. In order to discriminate T. lupinaster subsp. pacificum from T. lupinaster, we propose to use a coefficient which characterizes the obovateness of leaflet shape. Our clarification of the taxonomic status of narrow endemics and rare species from the genus Trifolium section Lupinaster has important implications for conservation purposes.