Morphological relationships among 15 species of Trifolium occurring in Poland

Populations of 15 Trifolium species were morphologically assayed to elucidate species relationships and taxonomic arrangements in the genus. Twenty-one characters were scored and analyzed by numerical methods. All species proved to be heterogenous. The levels of dissimilarity among populations of the same species ranged from around 0.05 to around 0.6. Cluster analysis divided all taxa into two major groups of species which were joined at D (Euclidean Distance) around 0.9. Within the first group three major sub-groups were revealed, comprising T. hybridum L., T. repens L., T. strepens Cr., T. dubium Sibth., T. campestre Schreb., T. patens Schreb. and T. fragiferum L. The second major group consisted of T. pannonicum L., T. arvense L., T. montanum L., T. incarnatum L., T. alpestre L., T. rubens L., T. pratense L. and T. medium L. The present results proved that the genus is very heterogenous, and support the hypothesis that the section Lotoidea was probably the stock from which other sections derived. Morphological relationships among 15 Trifolium species support their taxonomic arrangements proposed by Zohary & Heller (1984), with some exceptions. Sectional positions of T. montanum and T. strepens should be reexamined. Conspecific ranks for three species of section Chronosemum - T. dubium, T. campestre and T. patens - should be considered.