Nine taxa of Oryzeae that occur naturally in Thailand were studied for their lemma micromorphology using scanning electron microscopy. Common features found in most taxa were microhairs, prickles, silica bodies, and papillae. Here, features of the lemma surface are described, classified, and discussed in terms of their taxonomic significance. In addition, a key to species based on the shape of silica bodies, type of papillae and tubercles, and the arrangement of tubercles is presented. However, lemma micromorphology alone cannot be used to distinguish three species in the Oryza sativa group, namely, O. sativa, O. rufipogon, and O. officinalis.
