Taxonomic and floristic notes are provided about recent floristic account of Japanese Polygonaceae (Yonekura 2006), along with further additions and corrections. 1. Yonekura and Ohashi (1997)'s classification system of Polygonaceae is modified based on molecular phylogeny. 2. Additional comments are made about a few cultivated or naturalized genera of Rumiceae not treated in Yonekura (2006). 3-7. Floristic and taxonomic comments are made about Rumex acetosella (3), R. alpestris (4), R. nepalensis (5), R. madaio, R. longifolius, R. gmelinii and R. aquaticus (6) and R. dentatus (7) in Japan and its adjacent regions. Lectotype of R. madaio is designated.

Many hybrid taxa have been described in Potamogeton. These hybrids can usually be recognized by morphological intermediacy between parent species but in some cases recognition is difficult due to extensive morphological variation. Potamogeton xinbaensis Kadono which was reported as a hybrid between P. lucens L. subsp. sinicus (Migo) H. Hara var. teganumensis(Makino) H. Hara and P. wrightii Morong, is one of them. In this study nuclear and chloroplast DNA sequence confirmed this report and inferred P. wrightii as the maternal parent of the hybrid. Potamogeton xinbaensis was also found together with both parents a few years ago in artificial ponds near Inbanuma Lake, but no hybrid plants from opposite parental pairs were recognized. Considering geographic distance P. xinbaensis is inferred to have undergone hybridization events independently in Inbanuma Lake and in Oitoike Pond. Morphological analysis showed that leaf morphological characters partially overlap between P. xinbaensis and both of the parental taxa which suggests that identification based on leaf morphology needs careful examination and that molecular analysis is a more useful tool for recognition of hybrids.

Five species of the genus Carex collected from the Yakushima Island were subjected to karyomorphological analysis. Chromosome numbers of C. atroviridis (2n = 70), C. morrowii var. laxa (2n = 38) and C. odontostoma (2n = 30) were determined for the first time. Two taxa endemic to the Yakushima Island, C. atroviridis and C. morrowii var. laxa, had the same chromosome numbers as their allies, respectively. Carex warburgiana had a chromosome number of 2n = 28, which was new for this species. A chromosome number of 2n = 22 for C. grallatoria var. heteroclita corroborates previous reports. A dwarf type of C. odontostoma with a chromosome number of 2n = 30 was also found on the Yakushima Island. There were no karyomorphological differences between the dwarf and common types of C. odontostoma.

Seven Allium species collected in the Tianshan Mountains, Xinjiang, China were karyologically studied. They commonly showed the chromosome number of 2n = 16. The chromosome complement of 14m and two sm chromosomes was found in A. deserticolum and A. oreoprasum; 14m and two st chromosomes were found in A. globosum and A. platyspathum; 12m, 2sm, 2st chromosomes were found in A. caricoides; 12m and 4st chromosomes were found in A. korolkowi; 16m chromosomes were found in A. obliquum. Chromosome numbers and the karyotypes of A. caricoides and A. deserticolum are reported here for the first time.

Aconitum soyaense, a new species of subgenus Lycoctonum of the genus Aconitum is here described from Hokkaido, northern Japan. Aconitum soyaense is distinguished from A. gigas H. Lev. & Vaniot and A. umbrosum (Korsh.) Kom. by having sepals and carpels hirsute with smooth-surfaced hairs, rounded conical, short-beaked helmets, elongated divaricate branches, smaller seeds, larger nectary blades and leaf blades sericeous with long, smooth-surfaced appressed hairs. Aconitum soyaense is restricted to the serpentine area in northern Hokkaido and is considered to be a serpentinophyte.