Geographical distribution and morphological variation of Bistorta tenuicaulis (Bisset & S. Moore) Nakai are examined. Two types of plants are recognized in the species by the differences in rhizomes, radical leaves, inflorescences, pedicels and sex expression patterns. Plants from the Japan Sea side regions of central to western Honshu are recognized as a new variety, var. chionophila Yonekura & H. Ohashi. Gynodioecy of B. tenuicaulis is reported for the first time and compared with that of B. abukumensis.

Myelochroa denegans, a rare species known only from India and Sri Lanka, is first reported from Java, Indonesia. Myelochroa siamea characterized by the production of galbinic acid is described as new to science. The new species is more closely related to M. irrugans than to M. galbina, though it produces galbinic acid.

In order to obtain additional taxonomic information about infraspecific taxa of Petunia integrifolia, we examined reciprocal cross compatibility between combinations of var. integrifolia, var. depauperata, subsp. inflata, subsp. occidentalis, as well as P. axillaris. Subsp. occidentalis completely failed to set capsule when it was used as the pollen parent. Similarly, the crossings in the opposite direction were rarely successful, and the number of hybrid plants obtained was limited. In contrast, all other taxa, including P. axillaris, could be crossed reciprocally with a higher rate of capsule set. The pollen fertility of the subsp. occidentalis hybrid was inferior to that of all the other hybrids. Based on the results of a previous study (Ando et al. 1995) and those of the present one, we treated subsp. occidentalis as an independent species herein.

The development of embryo of Sarcandra glabra was described. The formation of embryo had the T-shaped proembryo at the beginning and the initial cells of the root-cortex were derived from the lowr tier of the cell m, so the embryonic development was conformed to the Polygonad type. It seems that the Chloranthaceae has closer affinity to the Polygonales and the Caryophyllales than the Magnoliales.

A fossil matoniaceous rhizome, Tricyclopteris japonocretacea gen. et sp. nov. is described from the Upper Cretaceous of Hokkaido, Japan. The rhizome has a tricyclic solenotele with endarch primary xylem. A matoniaceous petiole or rachis, Matoniostipes mesozoica Nishida (1973) from the Lower Cretaceous of Choshi, Chiba Prefecture, is emended and reexamined for comparison. It has loose parenchyma (Seward 1899) near protoxylem like the petiole of living Matonia pectinata. Matonia pectinata is also characterized by a small cavity parenchyma (Holder, 1925: Ogura, 1972) near protoxylem in the rhizome, while it does not occur in Tricyclopteris.

Biological study on the pollination of Lysichiton camtschatcense Schott was carried out at the Nida marsh, Fukushima Prefecture and the Oze-gahara moor, Gunma Prefecture, both in central Japan. Flowers are protogynous changing female to hermaphrodite at anthesis. The spadices are visited by a small number of insects. Polination is entomophilous as well as anemophilous. A bagging experiment showed that self-pollination is also possible.

During March through April 1997, Sasa kurilensis (Ruprecht) Makino & Shibata var. jotanii Inoue & Tanimoto (Poaceae: Bambusoideae) exhibited monocarpic mass flowering, beginning partially in the spring of 1996. Several clumps of the plant have been implanted from two distributing areas of Izu Islands; Mt. Oyama, Mikura-jima and Mt. Miharayama, Hachijo-jima into campuses of the Forestry and Forest Products Research Institute, Tsukuba and Utsunomiya University, Utsunomiya, Kanto District, Japan for 13 years. Another clump from Mt. Oyama has been implanted into Tsubota, Miyake-jima, 18 km North of Mikura-jima for more than 20 years. All these implanted clumps flowered at the same spring of 1997. While clumps from Mt. Miharayama did not exhibit flowering both in the native stand and two implanted sites. These facts showed that the mass flowering of S. kurilensis var. jotanii caused by endogenous or genetic factor(s), and not by any environmental factors; the populations in Mt. Oyama and Mt. Miharayama have a different history of establishment. The period of flowering cycle was estimated as 60 years, because an 80-years old villager remembered that last mass flowering had occured on the year at his 20-year-old.