The genus Leptosolena currently accepted as monotypic and endemic to the Philippines, has been considered as an imperfectly known genus due to the description based on insufficient herbarium materials

Anthecological observations on two Japanese orchids, Cyperipedium macranthos var. speciosum and Dactylorhiza aristata, were preliminarily carried out. The results suggested that nectarless flowers of

. Nectarless flowers of Cypripedium macranthos var. rebunense are pollinated by only queen Bombus pseudobaicalensis , which also pollinates nectar-producing flowers of Pedicularis schistostegia . Our previous study (Sugiura et al. 2001) suggested that they form a floral mimicry system: (1) Flowering phenology of both plants overlapped greatly. (2) Cypripedium occurred with lower frequency relative to Pedicularis . And (3) in a mixed stand of both plants, foraging bumblebees were sometimes confused between the mimic and model flowers. The present study clarified the system with new evidence. (4) Flower colour of Cypripedium and Pedicularis would be similar within the range of a bumblebee's visual spectrum. And (5) both species largely overlapped in spatial distribution. Based on these findings, we discuss how C. macranthos var. rebunense differs in pollination mechanism from other congeneric species, especially C. calceolus .

var. rebunense, was preliminarily studied on Rebun Island, Hokkaido, Japan, for conservation of this threatened orchid. The functional longevity of individual flowers varied from 0 to 18 days, a determining factor being the wind conditions at the growing sites. The flower was self-compatible but needed a pollen vector for fruit production. It lacked nectar and adopted a deceptive pollination system. Queens of a bumblebee, Bombus pseudo-baicalensis, were found to be pollinators but their visits were infrequent. Fruit set was 8.3% at one study site but only 1.2% at another, probably due to interference from the many visitors who came to see the flowers. Based on the results, conservation and management of lady's slipper were discussed. The need for less human interference and for preservation of the interactions between lady's slipper and its pollinator or other plant species with floral rewards is stressed.

A previous study of Campanula punctata pollinated by Bombus diversus showed greater male reproductive success in plants with wider corollas when male reproductive success was measured by paternity analysis. Pollen removal alone was not a good measure of male reproductive success. The aim of the current study is to elucidate the mechanism underlying the selection on corolla width in C. punctata. Multiple regression analysis of male reproductive success in experimental populations revealed that the advantage of a wide corolla to the male is independent of the corolla width of pollen recipients, indicating that the position of pollen deposited on Bombus may not be an important factor for selection. However, the number of pollen grains that fell on the petal or off the flower and were lost at the first visit of Bombus (pollen fall) decreased with increasing corolla width, so that most pollen grains removed from a wide flower were deposited onto the pollinator. In a narrow flower, a greater proportion of the pollen removed was wasted through pollen fall. Pollen removal does not reflect male reproductive success, at least in part because of the loss of pollen in some flowers through pollen fall. The positive relationship between wider corollas and reduced loss of pollen through pollen fall is likely to lead to greater male reproductive success of wider flowers under repeated visits of pollinators. Decreased pollen fall, probably due to more gentle contact between pollen and bees in flowers with wider corollas, may be one of the mechanisms underlying the selection on corolla width of C. punctata.

In order to conserve Aster kantoensis, the effects of local population size of Aster kantoensis on the pollinator visitation frequencies were studied in the middle course of the Tama River floodplain. The peak of pollinator visitation on A. kantoensis was between 10: 30 A. M. and 0: 30 P. M. The mean frequencies of pollinator visitation on the heads of A. kantoensis were correlated with the size of local population. The pollinator availability of A. kantoensis must be affected by the size of local population.

To identify the factors responsible for degrading the habitat of the endangered plant species Aster kantoensis , as well as the vulnerable life stage where this occurs, we carried out sowing experiments. Two natural habitats were simulated, being situated along the floodplains of the Tama River in central Japan. Seeds collected from a natural habitat were sown in two apparently suitable locations (Tomoda and Ishida sites). Germination, survival, growth, and seed production were subsequently monitored from 1993 through to 1997. The Tomoda site was a gravel bar in floodplains formed by flooding in 1991, while the Ishida site (two plots) was one gravel bar where several plants were growing sparsely and another where a population had become extinct in 1992. Seed cohorts completed their life cycle within 3 years at the Ishida site and within 5 years at the Tomoda site. Monitored parameters at Ishida were substantially lower than those at Tomoda. In addition, estimates of population growth indicated an increase at Tomoda and a rapid decrease at Ishida. However, degradation of habitats seemed to occur at Tomoda over the monitored periods. In view of our results, we conclude that natural germination of about 0.13% is needed for increasing population size. The major factors for decreasing population size are believed to be the lack of safe sites for germination and seedling establishment in old habitats (> 10 years). Conservation measures are suggested based on these findings.

多摩川におけるカワラノギクのメタ個体群の占有面積は近年大きく減少している. 局所個体群の全植被率とロゼット個体密度とには負の相関があり, 全植被率が60%以上になると局所個体群が衰退する傾向がみとめられた. しかし, 競合するほかの植物との競争だけでは局所個体群の衰退は説明できなかった. 写真上で解析した1×1cmの微小環境と実生の出現との関係から, カワラノギクの実生のセーフサイトは礫質河原において礫によって形成された陰であることが示唆された. 実生のセーフサイトを維持するためには大規模な増水によって砂が洗い流される必要があると考えられる.

Flowers exhibiting a large corolla encompassing a wide inner space, characteristic of bee-pollinated plant species, are postulated to be maintained by a natural selection mechanism related to their pollinators. To confirm the existence and to elucidate the mechanism of such selection, we investigated the effect of floral traits on male reproductive success (RS) and its components in experimental populations of Campanula punctata and C. microdonta (Campanulaceae) under pollination by Bombus diversus (Apidae). Larger corolla width significantly increased male RS per fruit, though there was no effect on pollen removal, showing, for the first time, that a wide corolla serves a reproductive function of enhancing pollen transfer efficiency (ratio of male RS to pollen removal). Selection by pollen transfer efficiency through an indirect effect of initial pollen number or postpollination success was experimentally ruled out. Several mechanisms are proposed to explain how this selection factor is exerted on C. punctata corollas.

To mitigate destruction of the Aster kantoensis population in the floodplain of the Tama River (Futyu City, Tokyo, Japan) by constructionof a bridge, Asterkantoensiswas transplantedby gathering its seeds and sowing them. Its survival rate in new sites was lower than the record in a preliminary experiment. This was presumably due to loss of safe sites for the seedling as voids in gravel were filled with sand.

we examined dormancy/germination traits of the seeds of Aster kantoensis, an endangered local endemic on the gravelly flood plains of a few, eastern central Japanese rivers, to assess its ability to form persistent soil seed banks in its natural habitats. Immediately after the seed collection from the largest remaining population of the River Tama in early, winter, the seeds showed a low level of relative dormancy, which disappeared within a month under the prevailing conditions in the natural habitat. After a few months' dry chilling storage, the seeds became germinable over a wide temperature range, i.e. 6-36 degrees C. The seeds showed neither requirement for temperature fluctuation nor sensitivity to leaf canopy light. The thermal time required for 50% germination at temperatures below 30 degrees C was less than 70 Kd (Kelvin days calculated with a base temperature of 5 degrees C). Since such requirements for germination of seeds naturally dispersed and overwintered will be satisfied by a spell of spring rain, we cannot expect the formation of persistent soil seed banks. Correspondingly, after spring germination, no or negligible firm intact seeds could be detected in the surface soils sampled.Safe-sites for the recruitment of the species are known to be new areas created by fluvial disturbance, which may occur sporadically in space and time. Without persistent soil seed banks, successful dispersal of the seeds to these safe-sites is of crucial importance for the persistence of the metapopulation composed of ephemeral subpopulations. Recent decrease in the colonization Fate of new subpopulations due to diminishing seed sources might accelerate the decline of the metapopulation. To break the extinction vortex in which the species has been involved, we propose human-aided seed dispersal to safe-sites in order to strengthen the conservation of this threatened species. (C) 1997 Published by Elsevier Science Ltd.

We sampled 17 populations of a rare autotetraploid Aster kantoensis (Asteraceae) from three river systems located in central Japan, and studied them for allelic variation at 22 enzyme loci. There was no significant correlation between the actual population size and three genetic diversity parameters, suggesting that the effective population size was very small even for the large populations, i.e., even large populations may still have a high probability of being of recent origin and remain influenced by the founder effect. Compared to other autotetraploid species, the total genetic variation of A. kantoensis is small. The number of alleles and gene diversity of a population were not significantly different among the river systems, although the percentage of polymorphic loci was different. Genetic differentiation among river systems was larger than between populations within the river systems, thereby indicating that gene flow between river systems is small, especially between the Kinu River system and Tama or Sagami River systems.

Aster kantoensis, an endangered plant species, is a local endemic on floodplains of a few rivers in eastern central Japan. Three years' demographic study (1989–1991) on several subpopulations (discrete patches of the plants) revealed that it is a monocarpic perennial with a 2- to 4-year vegetative growth phase before flowering. Its distribution on the floodplain is restricted to sparsely vegetated gravelly areas. A relatively high light requirement and low competitive ability to gain light are likely to be responsible for the distribution pattern. Demographic parameters obtained for the studied period indicate a decline of the subpopulations of A. kantoensis. In a transect covering 76 m2, mean viable seed production per flowering plant was 450 (1990) and 780 (1991), but less than 0.027% of dispersed seeds survived to the reproductive stage. The spatial and temporal patterns of disturbance are of critical importance for the maintenance of the metapopulation of this short-lived species without a persistent seed bank or vegetative reproduction.

カワラノギクの保全手法についての基礎的なデータを得るため, カワラノギクの生育地の微地形と植被率とを調査した。単位個体群を含む幅1mのベルトトランセクトを設定して, 群落調査と水準測量を行い, そのなかの1×1mの方形区の優占種力ワラノギクの有無, 植被率および水面からの高さを記録した。微地形は, 低水地, 流路斜面, 中水地, 中水地凹地, 高水地斜面, 高水地, 高水地凹地, 堤防法面, 人工改変地に区分した。カワラノギクは中水地に対する特化度が高く, 植被率が比較的低い方形区に分布していた。カワラノギクを保全するためには, 生育場所が類似し, 競合する帰化優占種であるオニウシノケグサとニセアカシアの繁茂を制御する必要がある。

多摩川におけるカワラノギクの個体群の分断化の進行と種子散布について調査した。1976年と1984年の植生図と1993年に行った現地調査から, 地域個体群の数は13, 8, 4と減少していた。地域個体群の間の距離が増大していたことから, カワラノギクの種子が生育可能なパッチに到達する確率は低下していると推定される。風散布, 付着散布, 水散布の3つの種子散布様式の散布距離を実験的に比較したところ, 前二者は散布距離が短く, 水散布のみが地域個体群間の種子散布に貢献できることが示唆された。水散布には方向性があるので, カワラノギクの保全には上流部に位置する地域個体群を保全することが重要であると考えられる。

To examine the response of pollinating bees to size and sexual phases of flowers, we constructed an artificial population ofCampanula having large flower variation and presented it to potentially pollinating bees in nurseries. The pollinating bee groups (halictid, megachilid and bumble bees) responded differentially to both the flower size and to the sexual phases of the flowers. Whereas visitation rate of megachilid bees increased with the flower size, those of halictid bees and bumble bees did not show particular trends; for example, bumble bees visited almost all of the flowers consistently. Visitation frequencies to male-and female-phased flowers were significantly different between megachilids at Tokyo and halictids. This study indicates that pollinator attraction could not solely explain the evolution of the flower size inCampanula, and that other factors such as pollen transfer efficiency, should be considered.

Plant Species BiologyVolume 9, Issue 2 p. 133-136 Factors Controlling the Recruitment of Aster kantoensis (Asteraceae) I. Breeding System and Pollination System KEN INOUE, KEN INOUE Biological Institute and Herbarium, Faculty of Liberal Arts, Shinshu University, Matsumoto, Nagano 390, JapanSearch for more papers by this authorIZUMI WASHITANI, IZUMI WASHITANI Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki 305, JapanSearch for more papers by this authorNOBORU KURAMOTO, NOBORU KURAMOTO Sakuragaoka Park Office, Tokyo Park Association, Tama, Tokyo 206, JapanSearch for more papers by this authorAKIO TAKENAKA, AKIO TAKENAKA National Institute for Environmental Studies, Tsukuba, Ibaraki 305, JapanSearch for more papers by this author KEN INOUE, KEN INOUE Biological Institute and Herbarium, Faculty of Liberal Arts, Shinshu University, Matsumoto, Nagano 390, JapanSearch for more papers by this authorIZUMI WASHITANI, IZUMI WASHITANI Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki 305, JapanSearch for more papers by this authorNOBORU KURAMOTO, NOBORU KURAMOTO Sakuragaoka Park Office, Tokyo Park Association, Tama, Tokyo 206, JapanSearch for more papers by this authorAKIO TAKENAKA, AKIO TAKENAKA National Institute for Environmental Studies, Tsukuba, Ibaraki 305, JapanSearch for more papers by this author First published: August 1994 https://doi.org/10.1111/j.1442-1984.1994.tb00093.xCitations: 13AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume9, Issue2August 1994Pages 133-136 RelatedInformation