ibclogo XVI International Botanical Congess


Abstract Number: 2276
Poster No. = 415


COMPARATIVE MORPHOLOGY OF DISK FLORET TRICHOMES OF ENCELIA (ASTERACEAE)


Kevin J. Carpenter & Curtis Clark, California St. Polytechnic Univ., Pomona and Rancho Santa Ana Botanic Garden, Claremont


Encelia consists of 15 species of shrubs of arid North and South America. Disk floret trichomes were examined with scanning electron microscopy to characterize complement, distribution, and to interpret their evolution in light of the phylogeny. Observed trichomes included narrow-based uniseriates, biseriate glands, and biseriate Zwillingshaare. Broad-based uniseriate, curly narrow-based uniseriate, and moniliform trichomes observed on foliar and cauline organs of the genus were absent. The Encelia disk floret trichomes generally display differences among species, but also extensive. Thus the trichomes are not generally phylogenetically informative. A notable exception involves E. halimifolia, E. palmeri, and E. farinosa, which are thought to form a clade, which is supported by the synapomorphy of no corolla glands.


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