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The pollination syndromes have been widely used to predict effective pollinators of plant species and provide the mechanistic explanation of floral diversity. However, in recent years, the predictive applicability of pollination syndromes has been frequently questioned. The accuracy of the syndromes among the closely related plant species may vary temporally and spatially. This suggests the need for the standardized, comprehensive evaluation of factors influencing the matching of a pollination syndrome of a plant species to the predominant pollinator community. We studied the pollination biology of three geographically/ phenologically isolated alpine gingers (Roscoea auriculata, Roscoea capitata, and Roscoea tumjensis) exhibiting the correlated suites of floral traits that suggest long-tongued insects as major pollinators, to test for the predictive power of the respective pollination syndrome. We also tested if geographical and temporal isolation affects interspecies breeding system and extent of pollinator generalization. We demonstrate that the three Roscoea species are self-compatible but lack autonomous selfing, and thus completely rely on pollinators for pollination success. Five years of observations demonstrate that only diurnal insect visitors foraged on the flowers of the three Roscoea species. Estimates of the pollinator importance (pollen deposition) of the observed floral visitors indicate that morphologically mismatched bumblebees contribute more than 90% of pollination service in all the three Roscoea species, while long-tongued butterflies and moths function as nectar robbers. We found that geographical isolation and temporal variation in flowering period does not affect the breeding system and pollinator generalization in the three Roscoea species. The three geographically and phenologically isolated Himalayan Roscoea spp., with long-tongued insect pollination syndrome, exhibit generalized pollination system and primarily rely on the morphologically mismatched Bombus species for pollination success. While, for three Roscoea spp., our result suggests that pollination syndromes are a weak predictor of efficient contemporary pollinator community, it also substantiates the role of non-pollinator agents for the evolution of floral traits. The evolution of Bombus pollination in these alpine gingers suggests how the mismatch between plant and pollinator phenology can lead to the emergence of novel reproductive strategies among the congeners, which ultimately seems to play a key role for the speciation and diversification of the genus Roscoea in the Himalayas. [ABSTRACT FROM AUTHOR]

Unlike the seriate lowland rain forests in SE Asia, the tropical vegetation of Xishuangbanna (SW China) has developed in habitats with comparatively lower temperatures and precipitation. Consequently, although most of the families and genera of the flora are components of tropical ecosystems, many have reached their distribution limits in latitude. Selection pressures on sexual systems in these environments may be different from that experienced in lowland tropical regions. Here, we examine the sexual systems of 685 species of flowering plants belonging to 109 families and 356 genera based on 42 plots with a total area of 15.4 ha and compare our results with surveys of sexual systems from other tropical ecosystems. Among these species, 60.6 percent were hermaphroditic, 14.3 percent were monoecious, and 25.1 percent were dioecious. The percentage of dioecious sexual system among tree species (26.1%) was similar or higher than that of other tropical tree floras. Monoecy was significantly associated with the tree growth form and was relatively common in seasonal forest vegetation. Sexual systems involving unisexual flowers (dicliny) are particularly well represented in the tropical forests of Xishuangbanna accounting for 39.4 percent of all species surveyed. This pattern may be associated with the prevalence of relatively small inconspicuous flowers in the tropical forests of SE Asia and their correlation with diclinous sexual systems generally. [ABSTRACT FROM AUTHOR]

Rhynchanthus beesianus W. W. Smith (Zingiberaceae) is an epiphytic tropical ginger with a very conspicuous floral display, but almost no fruit set under field conditions. The reproductive ecology encompassing phenology, floral biology, and pollination and breeding systems was investigated in an evergreen broad-leaved forest in Yunnan Province, Southwest China. The flowers possess a typical bird pollination syndrome, but no effective pollinators were observed during 138 h of observation. Female Black-breasted Sunbird ( Aethopyga saturata) and bumblebees visited R. beesianus regularly, but they all played roles as nectar robbers. No fruit was found in the bagging treatment, and fruit set following manual self-pollination ((57.55 ± 4.08)%) was comparable with cross-pollination ((64.32 ± 4.42)%), suggesting that R. beesianus is self-compatible but spontaneous self-pollination in this species does not occur. Seed set of open-pollination ((26.42 ± 3.11)%) was significantly lower than manual self-pollination ((73.41 ± 4.16)%) and cross-pollination ((75.56 ± 4.52)%), confirming that R. beesianus was dependent on animals for fertilization and suffered a serious pollinator-limitation. (Managing editor: Wei Wang) [ABSTRACT FROM AUTHOR]

Tacca, a genus of tropical herbs, possesses near black flowers, conspicuous involueral bracts and whisker-like filiform bracteoles. These features have been assumed to function as a ‘deceit syndrome’ in which reproductive structures resemble decaying organic material attracting flies that facilitate cross-pollination (sapromyiophily). We investigated pollination and mating in Tacca chantrieri populations from SW China to evaluate this assumption. Contrary to this expectation, populations were highly selling. Pollinator visitation was infrequent and bagged flowers set abundant seed. Pollen loads on stigmas indicated autonomous self-pollination, some of which occurred prior to flower opening. The seed set of inflorescences with bracts and bracteoles removed was not significantly different from unmanipulated inflorescences, suggesting that these structures play a limited role in pollinator attraction, at least at our study sites. Pollen ovule ratios averaged 49, a value expected in a highly selling species. Selfing rates estimated in four populations using allozyme markers averaged 0.86 (range 0.76–0.94), thus corroborating this inference. Our results indicate that despite considerable investment in extravagant display, populations of T chantrieri are highly selling. We propose several hypotheses to resolve this paradox and argue that future studies of pollination syndromes would benefit by investigation of both pollination and mating biology. [ABSTRACT FROM AUTHOR]

Alpinia is the largest, most widespread, and most taxonomically complex genus in the Zingiberaceac with 230 species occurring throughout tropical and subtropical Asia. Species of Alpinia often predominate, in the understory of, forests, while others are important ornamentals and medicinals. Investigations of the evolutionary relationships of a subset of species of Alpinia using DNA sequence- based methods specifically test the monophyly of the genus and the validity of the previous, classifications. Seventy-two species of Alpinia, 27 non-Alpinia species in the subfamily Alpinioideae, eight species in the subfamily Zingiberoideae, one species in the subfamily Tamijioideae, and three. species in the' outgroup genus Siphonochilus (Siphonochiloideae) were sequenced for the plastid matK region and the nuclear internal transcribed spacer (ITS) loci. Parsimony analyses of both individual and combined data sets identified six polyphyletic clades containing species of Alpinia distributed across the tribe Alpinieae. These results were supported by a Bayesian analysis of the combined data set, Except in a few specific cases, these monophyletic groupings of species do not correspond with either Schumann's (1904) or Smith's (1990) classification of the genus. Here we build on previous molecular analyses of the Alp inioideae and propose the next steps necessary to recognize new generic boundaries in the Alpinieae. [ABSTRACT FROM AUTHOR]

Curcumorpha longiflora is a perennial chasmophyte (rock fissure plant) ginger that usually grows in crevices of calcareous rocks and forms patches on the understory of limestone monsoon rainforests. The pollination ecology of C. longiflora was studied by monitoring phenology and flowering behavior, observing pollinator activity (frequency and behavior of visitors), and the quantity and quality of pollination services. We also investigated the germination of pollen grains and growth of pollen tubes after different pollination treatments to detect its breeding system. Based on the results: (1) for the first time in Zingiberaceae a new protandrous mechanism was found with a two-day flowering to avoid autogamy in this species; (2) under field conditions, all individuals of C. longiflora usually produced only one flower every other day to keep geitonogamy to a minimum; (3) germination of pollen grains and growth rates of pollen tubes under different pollination treatments were the same 4 h later after pollination, suggesting that C. longiflora is completely self-compatible; (4) among the limited visitors, Bombus sp. and Apis florae were effective pollinators, but they were active at different times and at different stages of the flower, probably receiving different rewards. [ABSTRACT FROM AUTHOR]