Pemphis acidula J. R. Forst. & G. Forst. (Lythraceae) has been speculated to show distyly derived from tristyly by loss of the mid (M)-styled morph. To understand morphological and reproductive natures and pollinators effective for pollination we examined floral variation, fruit and seed production by pollination experiments, and flower visitors in four natural populations of P. acidula occurring in Taiwan and Japan. The populations examined were commonly distylous with long (L)- and short (S)-styled morphs, but each morph had anthers arranged at two different levels, as in some other populations of the species reported earlier. Pollen grains were significantly larger in the S-styled morph than in the L-styled one, but there was no significant difference in pollen size between the two anthers from different levels. Furthermore, artificial pollination experiments indicated that the two morphs exhibited self and intramorphic incompatibility, and the middle-level anther had the same compatibility as the other-level anther of the same morph. These results suggest that the pollen size and the compatibility system have a distylous nature in the examined populations, despite the fact that the anthers are arranged in two different levels in each morph. Short-tongued bees and aculeate wasps frequently visited the flowers for sucking nectar and touched their mouthpart to the stigma and the anthers, suggesting that they may be the most efficient pollinators for completing crosspollination between the two morphs at the Iriomote population of the species.

A new locality for Potamogeton lucens L. (Potamogetonaceae) was recorded from a pond in Aomori Pref., Tohoku District, Japan. In Japan, this species is critically endangered, and the sole remaining naturally established population was previously known only from one other locality. In June 2017, we found fragments of a submerged plant species that resembled P. lucens. We conducted field surveys and identified it as P. lucens based on morphological measurements, nuclear and chloroplast molecular analyses, a herbarium specimen survey, and pollen fertility. Although we could not reveal its population size and distribution in the pond, at least an established population exists because many fragments and a plant with developed roots were collected. This new locality of P. lucens represents the new northern limit of the species in Japan, which is over 500 km away from its nearest distributional record. As developments are now in progress around the pond area, urgent protection by a conservation program is needed.

Of about 180 species of Arisaema (Araceae), 53 species are distributed in Japan. In Japanese Arisaema, the Arisaema serratum group includes many species difficult to distinguish from each other because of a lack of decisive taxonomic characters between them. In May 2014, the fi rst author found that some populations of the Arisaema serratum group occur with A. ovale Nakai in Ohgaya, Nishiawakura-son, Aida-gun, Okayama Pref., western Japan. We have observed their native ecological and morphological features in the fi eld and compared with other populations in neighbouring areas. As a result, the populations were composed of four Arisaema species: A. maekawae J. Murata & S. Kakishima, A. angustatum Franch. & Sav., A. peninsulae Nakai, and A. pseudoangustatum Seriz. var. pseudoangustatum.

A natural hybrid, Carex ×ishimaensis J. Oda, S. Kinosh. & Nagam., was described from Ishima Isl., Tokushima Pref., Shikoku, Japan. This plant was presumed to be a hybrid between two species of sect. Rhomboidales, Carex boottiana Hook. & Arn. and C. subdita Ohwi, judging from the observations of habitat, gross morphology, pollen stainability, achene fertility, chromosome number and meiotic confi gurations. This is the fi rst report of the intra-sectional hybrid in the sect. Rhomboidales.

Calanthe puberula Lindl. var. okushiriensis (Miyabe & Tatew.) M. Hiroe, which is regarded as an endemic plant of Hokkaido (Okushiri Island) and Aomori Prefecture, northern Japan is distinguished from the typical variety C. puberula var. puberula by the hairy character of the undersurface of leaves. The hairs on the undersurface of leaves were found to fall off easily. After examining herbarium specimens, specimens with hairy leaves were newly found also from Chiba, Shizuoka, Wakayama, Nagasaki, and Kumamoto Prefectures, central and western Japan. Therefore C. puberula var. okushiriensis was suggested to be widely distributed in Japan.

Cephalanthera erecta (Thunb.) Blume var. oblanceolata N. Pearce & P. J. Cribb (Orchidaceae) is reported from west and central Nepal. This is a new record for the flora of Nepal, and the western most distribution for the species. A brief note with habitat and distribution is provided.