Abstract: Based on the field survey and literature review, the species composition, distribution, origin, life form, invasion habitat, damage degree, and invasion track of alien plants in limestone regions of Hainan Island were studied, and compared with those in neighboring regions. The results showed that in the limestone regions of Hainan Island, there were 53 species of alien plants, belonging to 45 genera and 22 families. Most of the alien species (77.4%) were originated from tropical America, and many of them (77.4%) were herbs. These alien plants were introduced by intentional (47.2%) or unconscious (35.8%) human activities. They were mainly distributed in the hillsides, margins or gaps of forests, and croplands at low altitude, and a few of them were found in the forests at high altitude. Through the comparison with those in neighboring regions, it was found that the alien plants in the limestone regions in Hainan Island could more easily invade islands and littorals than invade inlands, and the total number of the alien plants and its proportion to the native plants were closely related to human activities such as frequent foreign trade.

Key words: Vegetable, Nitrite, Pollution