Abstract: A alien plant species , Sysimbrium orientale L . (Brassicaceae ) is recorded in Yunnan , China in the paper . The species has been found invading the ecosystems of croplands and grasslands in Australia . Although it was previously recorded in China, there′s no alert report about it .Because the very small and mass-produced seed in siliques was dispersed by wind , the species can be potentially invasive . The result of our investigation indicated that there was a spreading trend of S. orientale in suburbs of Kunming, Central Yunnan . The biological characteristics and current status in Kunming were reported. We appealed to relevant government departments to make efforts to make a further investigation of its distribution and its invasion route . Assessment of its invasiveness in China is needed to eradicate it as early as possible to avoid its diffusion .

Key words: Sisymbrium orientale, Biological invasion