Abstract: Camellia changii is an endangered plant species endemic to China, and only confined to the E’huangzhang Nature Reserve in Yangchun City of Guangdong Province. In this paper, an experimental study was conducted on the out-crossing index (OCI), pollen-ovule ratio (P/O), and controlled pollination treatment of natural C. changii  population in the reserve, with the causes of its endangering approached. It was found that C. changii was a typical insect-pollinated plant species, with its breeding system out-crossing and self-incompatible. Its ovary had a high abortion rate (64%) under natural conditions. The style height of the C. changii population was apparently differentiated in length, i.e., 20% were long-morph (type L), and 76% were short-morph (type S). Butterflies and bees were the main effective pollinators of C. changii, but their visiting frequency was low. Based on the experimental results, the major causes of the endangering of C. changii could be (1) the high abortion rate of its ovary due to the self-incompatibility and heterostyly, and (2) the low fruiting rate due to the low visiting frequency of pollinators.

Key words: Brachionus angularis, Strain, Developmental period (De), Pre-reproductive period (Dp), Body size, Egg size