Pollen recovery was poor, ranging from 37 (Mae Moh) to 1195 (Chiang Muan) grains counted per sample, the average being ca. 416. Modern (Linnaean) family and genus names were used for the identified taxa. The fossil palynomorphs were directly compared to palynological references. A published SE Asia Flora and the ISEM palynological reference collection (48 000 slides of angiosperms, 2400 gymnosperms,2000 pteridophytes) were used as well to identify palynomorphs. The state of preservation of palynomorphs was very poor: 15% were so strongly corroded that it was impossible to describe them. The poor state of preservation of the pollen grains might be explained by oxidation during fossilization (Hoorn et al., 2000). Indeterminable grains (corroded, indescribable grains) were distinguished from uniden-
tified (i.e. unknown) grains, which have been described but not referred to any taxon.