XVI International Botanical Congess

Pollen and stigma of five species of the genus Desmodium in Mexico were studied under SEM to help classify D. amplifolium, D. conzattii, D. densiflorum, D. jaliscanum and D. sumichrastii (Subtribe Desmodiinae). All species have tricolporate pollen with a lalongate colpus. Traces of operculum were found in D. amplifolium and D. conzattii contrasting Ferguson & Skavarla's hypotheses. They all had costae-colpi, except D. conzattii. The margo varied in thickness and ornamentation, psilate or rugulate. Differences were found in the aperture membrane ornamentation. Pollen grain ornamentation was rugulate except for D. sumichrastii and D. jaliscanum, which were corrugated. The stigmas were conical in all and spherical in D. sumuchrastii, were remarkable differences were found. Pollen data suggests that these species, except D. sumichrastii, should be included in Shiang-Jiuun and Tseng-Chieng's group IV.