Biological Characteristics of the Critically Endangered Species Hibiscus yunnanensis Population

Hibiscus yunnanensis is one of the critically endangered（CR）species in the China Species Red List. The geographic distribution, habitat conditions, population status, growth and morphological characteristics of H. yunnanensis were surveyed, and the reasons leading to the critically endangered status were analyzed. According to the previous records, two old distribution spots of H. yunnanensis were found adjacent to Kunluo highway and close to Donge gas station, three new distribution points were discovered close to Wusa Village, adjacent to the Overseas Chinese Farm, and by the Agricultural Science and Technology Extension Station of Yuanjiang County. H. yunnanensis is a heliophilous subshrub species, not drought resistant, it usually grows in the sunny but moist habitats, whose accompany plants are mainly tropical heliophilous secondary species. H. yunnanensis plants do not generate root suckers, and do not fall easily. There are seldom seedlings in the H. yunnanensis communities although the adult plants may regularly blossom and bear fruits, with long florescence duration and large quantity of fruits. The distribution area of H. yunnanensis is shrinking, and the number of the plants has decreased rapidly, showing the overall declining trend. It was proposed that the human interference has been the main reason to cause the sharp reduction of H. yunnanensis plant number in the wild populations. The limitation of its self pollination, the spreading way of its seeds by gravity and the poor ability of natural regeneration might be the internal reasons leading to be extremely endangered.