Cypsela’s Morphology of Symphyotrichum Nees (Asteraceae)

The cypsela’s pubescence and exocarp structure of 17 species and hybrids (21 specimens) of the North American genus Symphyotrichum Nees (Asteraceae) introduced in botanical gardens of Europe are analyzed. The studied species are the following: S. chilense, S. ciliolatum, S. cordifolium, S. dumosum, S. ericoides, S. foliaceum, S. laeve, S. lateriflorum, S. novae-angliae, S. novi-belgii, S. puniceum, S. × salignum, S. shortii, S. tradescantii and S. × versicolor. The morphological parameters of the cypselae and trichomes were determined using a Keyence VHX-1000 digital electron microscope; the exocarp structure was analyzed with a LEO-1430 VP scanning electron microscope. Original data on the size of the cypselae and exocarp structure are presented. The groups of species are distinguished by the degree of cypsela’s pubescence and by the length of the trichomes. Some characteristics that can be used as additional diagnostic characters for taxonomic division have been revealed. A table for determining species by morphological features of the cypselae has been developed.