Distribution patterns of clonal plants in the subnival belt of the Hengduan Mountains, SW China.

Clonal reproduction (i.e., production of potentially independent offspring by vegetative growth) is thought to provide plants with reproductive assurance. Thus, studying the evolution of clonal reproduction in local floras is crucial for our understanding of the adaptive mechanisms plants deploy in stressful environments such as alpine regions. In this study, we characterized clonal plant species in the subnival belt of the Hengduan Mountains (a global biodiversity hotspot with extreme environmental conditions in southwest China), in order to determine the effects of sex system, growth form, and elevational distribution on clonality. We compiled clonality data of angiosperm species belonging to 41 families in the subnival belt of the Hengduan Mountains using published information. Of the 793 species recorded in the region, 47.92% (380 species) are clonal species. Both sex system and growth form had significant effects on the occurrence of clonal reproduction: unisexual species (79.79%) were more likely to be clonal than bisexual species (43.63%), and herbaceous species (51.04%) were more likely to be clonal than woody species (16.67%). Compared with non-alpine-endemic species (44.60%), alpine-endemic species (58.33%) showed a significantly higher proportion of clonal reproduction. Further logistic regression analysis showed a positive association between incidence of clonality and elevational range, indicating that species distributed at high elevations are more likely to be clonal. Furthermore, the elevational gradients in clonality were contingent on sex system or growth form. This study reveals that plants in the subnival belt of the Hengduan Mountains might optimize their probability of reproduction through clonal reproduction, a finding that adds to our growing understanding of plant's adaptations to harsh alpine environments.

Validation of Gastrochilus prionophyllus (Vandeae, Orchidaceae), a new species from Yunnan Province, China.

Gastrochilus prionophyllus, which was previously not validly published, is here validated. The species is described along with illustration and photos. Morphologically, the long and pendulous stem and distichous leaves of this new species indicate that it belongs to the sect. Microphyllae. It is unique in having thick fleshy leaves and margin significantly serrate, small flowers, reniform epichile and margin with dentations, thickened cushion on the central epichile and subconic hypochile. Meanwhile, a preliminary conservation status assessment according to IUCN Red List categories and criteria is given to the new species.