APPLICATION OF ACHENE MORPHOLOGY IN SYSTEMATICS OF SOME IRANIAN TARAXACUM (ASTERACEAE TRIBE CICHORIEAE) SPECIES

Achene micro-morphology of ۱۷ species of Taraxacum (Asteraceae) is investigated using Scanning Electron Microscopy (SEM). In this study ۱۲ qualitative and quantitative characters such as achene length, width and colour, ornamentation type and size, length of beak, length and colour of pappus were examined. Cluster Analysis (CA) and Principal Component Analysis (PCA) of data showed that micromorphology of achene has significant role in separating species from each other and it does support the delimitation at sectional level. Our results showed that ornamentation on achene body cannot be used in separation of taxa at species level as well as sectional rank, whereas ornamentation size showed to be a better tool for separation of species. Since fruit micromorphology provides some evidences for delimitation of species and sections, the results then were compared with the phylogenetic trees obtained from Maximum Parsimony (MP) and the Bayesian analysis (BA) of the nrDNA ITS region. Our results showed that current taxonomic system of the genus Taraxacum is not compatible with its phylogeny.

کلیدواژه ها:

Achene micromorphology ، Asteraceae ، Iran ، nrDNA ITS ، Taraxacum phylogeny