Summary1. An animal-pollinated plant living on a slope should orientate its flowers down-slope towards the more open space if by doing so it receives more pollinator visits and thereby achieves increased reproductive success. 2. We measured flower orientation relative to slope direction on individuals of 10 species of forest-floor herbs in cool temperate forests in Japan. For one of these species, Erythronium japonicum, we also manipulated flower orientation to test experimentally for its effects on both male and female reproductive function. 3. In all 10 species, flowers were preferentially orientated down-slope. This pattern was more pronounced in plants growing on steeper slopes. 4. Our manipulative field experiment in Erythronium japonicum demonstrated that pollen dispatch was highest in flowers orientated down-slope. Additionally, flowers orientated up-slope may have achieved a lower seed set on steep slopes. 5. We conclude that down-slope orientation of flowers was a general phenomenon among the species that we studied, and that this behaviour was adaptive in enhancing plant fitness through pollination.

The oxidation level of P700 induced by far-red light (DeltaA(FR)) in briefly dark-treated leaves of some sun plants decreased during the daytime and recovered at night. The dark recovery of decreased DeltaA(FR) proceeded slowly, with a half-time of about 5 h. We propose that stromal over-reduction induced by sunlight was the direct cause of the depression of DeltaA(FR). The depression of DeltaA(FR) found during the daytime was reproduced by controlled illumination with saturating light of fully dark-treated leaves. Simultaneous measurement of P700 redox and chlorophyll fluorescence showed that the depression of DeltaA(FR) was associated with dark reduction of the plastoquinone pool, which represented cyclic electron transport activity. The decrease of DeltaA(FR) in the light-stressed chloroplasts was partly reversed by treatment with 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone, an inhibitor of electron transport at the cytochrome b6/f complex, and the subsequent addition of methyl viologen, an efficient electron acceptor from photosystem I (PSI), stimulated further recovery, showing that both cyclic electron flow around PSI and the charge recombination within PSI were responsible for the light-induced depression of DeltaA(FR). The dark level of blue-green fluorescence, an indicator of NAD(P)H concentration, from intact chloroplasts was increased by high-light stress, suggesting that NADPH accumulated in stroma as a result of the high-light treatment. Possible effects on photosynthetic activity of over-reduction and its physiological relevance are discussed.

We investigated the genetic structure of Sciadopitys verticillata, an endemic conifer in Japan, using 11 microsatellite markers. Average expected heterozygosity varied from 0.282 to 0.450, with between 2 and 17 alleles per locus, and allelic richness varied from 2.14 to 2.94 within a population. Wilcoxon signed-rank tests suggested that there was a recent bottleneck in the southwestern populations in the Kinki district and in isolated northeastern populations in the Tohoku district. Bayesian clustering analysis showed that the populations of the Chubu, Kinki, and Shikoku districts were admixed from several clusters. Archaeological data suggest past anthropogenic exploitation for building and coffin material.

We aimed to determine the evolutionary patterns of plants, especially focusing on plants that occur in habitats composed of ultramafic rock. We carried out molecular phylogenetic analyses of the infraspecific taxa of Erigeron thunbergii composed of varieties and the closely related species Erigeron miyabeanus. Most of these plants are distributed in serpentine, peridotite, limestone, diabase and non-ultramafic areas of high mountains, meadows and seashores in Japan. Using data derived from sequencing the internal transcribed spacer (ITS1, 5.8S ribosomal DNA and ITS2) regions of nuclear ribosomal DNA, we identified Clade 1, which was composed of populations from Hokkaido Island and the north-east Honshu district group, and Clade 2, which was comprised of populations from central Honshu Island, Oga Peninsula and Mt Shokanbetsu. In addition, we identified three subclades within Clade 2 in detail. The phylogenetic tree showed the possibility of two major Erigeron phylogenies, that is, from the Kamchatka Peninsula and the Chinese continent. Moreover, the plants distributed in serpentine soils on Mt Yubari and in Shimukappu showed phylogenetically closer relationships than plants distributed in more closely located non-ultramafic sites.

We studied vegetation changes in a small floating mat bog in Mizorogaike Pond (Kyoto, Japan), which had experienced a severe decrease in the number and area of hummocks caused by nutrient loading in the 1960s and 1970s, to examine whether reducing the extent of nutrient loading can restore degraded wetland vegetation. However, nutrient loading in the region has been minimized since the 1980s. We examined the distributions of hummocks and Sphagnum cuspidatum mats in 1980, 1988, and 2006, as well as nine major vascular plants that dominated the hollows on the floating mat in 1980 and 2006. The total area of normal hummocks formed by Sphagnum palustre increased from 5865.3 m 2 in 1980 to 5913.6 m 2 in 1988 and 8485.2 m 2 in 2006. The total area of the S. cuspidatum mats also changed, from 416.4 m 2 in 1980 to 322.3 m 2 in 1988 and 1012.5 m 2 in 2006. Examination of the spatial distribution patterns of major plants revealed that emergent plants decreased in the northern part of the mat, but increased in the southern part.Thus, the improved pond water quality was effective at restoring hummocks, although nutrient loading may have caused some irreversible changes in the wetland vegetation.