Argyreia Lour. is one of the most taxonomically complex genera of the morning glory family (Convolvulaceae). The number of named species is now 135, and new species are regularly being described. There are several species complexes that are morphologically similar and difficult to tell apart. Therefore, the aim of this study is to explore the species identification criteria for Argyreia, especially new sources for taxonomically informative characters. Ten accessions representing three morphologically similar Argyreia operational taxonomic units (OTUs) were collected and their anatomical characters were investigated using the leaf peeling technique and paraffin sectioning method. Anatomical character states were analyzed using two phenetic analysis methods: clustering analysis (CA) and principal component analysis (PCA). Three distinct clusters were clearly separated in both PCA and CA at the internal similarity coefficient of 0.48 with a high R-value of 0.89757. Nineteen effectively distinguishable character states were derived from the high loadings of the first two components. In conclusion, two of the separated groups were matched with known species, and the third separated group is here delineated as a new species. Therefore, a new species, Argyreia gyrobracteata Traiperm & Chitchak, is described and illustrated together with ecological data and a preliminary conservation assessment.

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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.

Maesa brevipedicellata, a new species of Maesa ( Primulaceae-Maesoideae) from Papua New Guinea, is described and illustrated based on herbarium specimen observations. The collections of this species resemble M. rufovillosa and were previously determined as that species. Maesa brevipedicellata is unique with its self- supporting habit, hispid hairs throughout and paniculate inflorescences with very short pedicels. This new species mainly differs from M. rufovillosa by the habit (tree/shrub in M. brevipedicellata vs climber in M. rufovillosa) and the inflorescence structure (panicles in M. brevipedicellata vs simple racemes in M. rufovillosa).

Six new species of Maesa (Primulaceae-Maesoideae) from Papua New Guinea, namely M. angustibracteolata, M. aurulenta, M. brassii, M. oblanceolatifolia, M. pusilliflora and M. prolatifructa are described and illustrated based on observations from herbarium specimens; the taxonomic affinities of each species are also discussed.