Study on exotic weeds in Shandong Province

Sixty- five species of exotic weeds belonging to 22 families and 46 genera were identified and recorded in Shandong Provincethrough investigation and referring to the literatures. 50.77% of the exotic weeds originated from America. Concerning the introduction ways,46.7% of the exotic weeds were introduced as useful plants, while the others were introduced accidentally in accompany with transportation,imports of agricultural products, etc. Based on the grade of abundance, the exotic weeds of Shandong Province can be divided into 4 types.In this paper ,the author also discussed the influence in economy and entironment and put forward the countermeasure in cortroling theseexotic weeds.