Five new species of the genus Plagiostachys (Zingiberaceae) from Borneo, P. brevicalcarata, P. longicaudata, P. megacarpa, P. roseiflora, and P. viridisepala are described and illustrated. Of these, P. brevicalcarata, P. longicaudata, and P. viridisepala have mucilaginous inflorescences, while the inflorescences of the other two species are non-mucilaginous. A key to the Bornean species of Plagiostachys is also provided.

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A new genus and species, Myxochlamys mullerensis (Zingiberaceae) from Central Kalimantan, Borneo is described. This new species is characterized by indistinct pseudostems; congested inflorescences with spirally arranged bracts; copious, highly viscous, axillary-pooled mucus secreted from glands on imbricate bracts; and flowers with a concave labellum, versatile anthers, and a groove formed by the inner surface of the corolla tube to envelope and hold the style. Parallel orientation of the plane of distichy of the leafy shoots, well-developed staminodes, and labellum not connate with the filament suggest that Myxochlamys belongs to the tribe Zingibereae. Among the genera in Zingibereae, Myxochlamys is similar to Scaphochlamys in that it lacks a distinct pseudostem and spiral inflorescence; it is distinct from Scaphochlamys, however, in that it has a groove within the corolla tube, concave labellum and versatile anthers. Phylogenetic analyses based on DNA sequences of the nuclear internal transcribed spacer (ITS) and maturase K (matK) of the chloroplast DNA show similarity with Distichochlamys, Myxochlamys, and Scaphochlamys. The similarities and differences between Myxochlamys and related genera are discussed.

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Three new taxa of the Piperaceae, Piper betloides A. Chaveerach & A. Tanomtong, P. pedicellatum var. eglandulatum A. Chaveerach & P. Mokkamul and P. thomsonii var. trichostigma A. Chaveerach & R. Sudmoon are described and illustrated. Morphological differences between the new species and related taxa are also discussed.

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Based on a specimen from Guangxi, China, Ophiopogon ogisui (Asparagaceae) is newly described. This species is similar to O. tonkinensis, but differs from it in the urceolate flowers with a long pedicel.

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The morphology, allozyme variation and pollen viability in nine populations of Nuphar japonica, N. submersa, and unidentified intermediate plants were examined. A phenogram based on cluster analysis using 10 morphological characters revealed three cluster groups. Groups 1 and 3 had distinctive morphological characteristics and corresponded to the published descriptions of TV. japonica and N. submersa, respectively, whereas Group 2 showed intermediate values in most characteristics between the two species. In the allozyme study, many morphologically intermediate plants showed additive combinations of species-specific alleles in two loci (lapl and mdh3) from the two species. Pollen viability was significantly lower in intermediate plants than in the two species. Based on the evidence, we concluded that the intermediate plants were of hybrid origin between N. japonica and N. submersa and described them as N.×fluminalis.

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Through field observations, we concluded that Cayratia tenuifolia (Wight & Arn.) Gagnep. is distinct from C. japonica (Thunb.) Gagnep., although it is sometimes treated as a synonym of C. japonica. The floral disk of C. tenuifolia is yellow at anthesis and white after anthesis and the mature fruits are depressed obpyriform. In C. japonica the disk is orange at anthesis and becomes pink after anthesis and the fruits are globular. The chromosome number of C. tenuifolia is 2n=40.

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