Search

Chenorchis, a new orchid genus belonging to C. singchii with tropical orchid features, was found in subtropical regions of Gaoligong Mountain in Yunnan Province, China. This taxon undoubtedly belongs to Trib. Vandeae due to its comparatively advanced epiphytic and monopodial characteristics with very hard pollinia and long stipe. It is akin to Ascocentrum and Holcoglossum, from which it differs by its lip lacking appendage, side-lobes arising from both sides of the mid-lobe rather than the entrance to the spur; large stigmatic cave; very large rostellum, conspicuously broader than the column, spreading downward; pollinia each with a distinct caudicle attached to the incurved subterminal portion of a common stipe. Phylogenetic analysis shows that it may be of tropical region originally and evolve into a new genus due to changed environment, indicating that the main motivation of angiosperm differentiation is to bring forth more ecological opportunities. A further examination of reproductive ecology, especially pollination mechanism and breeding system, proved that this species has formed many mechanisms to promote selfing and inbreeding, such as symbiosis with ants (Temnothorax sp.), utilization of ants for short-distant pollination, opening of flowers simultaneously to increase the frequency of geitonogamy, efficient dispersal and growth of seeds, and crowded communities to improve the possibility of inbreeding. All the adaptive changes above turn into necessary conditions for their survival in subtropical regions. The reproductive strategy of this unique life history shows that this immigrant species autonomously passes the genes on to future generations to remain their adaptability, by quickly occupying the habitat. It is a successful strategy in habitat expansion that inflorescence produces a lot of flowers to facilitate geitonogamy, whose significance may extend to provide evidence that the occurrence of plants' sex results from the trade-offs of the fluctuation of habitat in evolution.

Trias, an orchid genus, was reported in this paper from China as a newly recorded genus for the first time. The genus and its new species, T. verrucosa Z. J. Liu, L. J. Chen et S. P. Lei, were described and discussed. Trias consists of 19 species ranging from Assam of India to Indonesia and Australia in the southeast via Myanmar to Deccan of India in the southwest. Its occurrence in West Yunnan of China is a further indication of phytogeographical relations between this region and the tropical Asia. This new species grows on shady rocks in forests. By observing of its biological characteristics such as phenology and blooming biology, lots of cloned ramets of generation overlap were found, but there were no fruited plants, and that clonal reproduction could repeat had nothing to do with whether the ramet bloomed or not. The flowering season of this species is from early April to early May. The opening of flowers on plants or inflorescence was irregular and the florescence of single flowers was rather short, only lasting 4–5 d, and no fruited flowers were found. Based on the detection of mating systems, no flowers of artificial self-pollination and artificial cross-pollination have fruited. Since the flowering period is just before the rainy season in this region, the ecological conditions of dryness, strong wind, low temperature and weak light during that period of time are evidently unfavorable to plant blooming, pollinating and fruiting. Apparently, the short duration and sterility of each flower would avoid the invalid energy waste in unfavorable circumstances and save the limited energy for more valid asexual reproduction so that the opportunity of multiplication in an uncertain environment would be increased to ensure the progenitive success. The P/O value of T. verrucosa is 187.4 ± 22.4, which is obviously related with the highly valid usage of its conglutinated and hard tuberous pollinarium during pollination, indicating that this species could hold the characteristic of sexual reproduction. This is an adaptation of this type of plants to the rather atrocious ecological circumstance there by its reproduction strategy of strengthening asexual reproduction and weakening sexual reproduction, and so it enables the plants to survive in this region, long-distanced from the places where its relatives dwell.