Nationally, ailanthus has become an agricultural pest and may occur as seedlings that pop up by the hundreds in recently planted fields, or as persistent thickets in rocky, untillable areas. The species was also brought into California mainly by the Chinese who came to California during the goldrush in the mid-1800s. Today it is frequently found in abandoned mining sites there. The history of ailanthus in China is as old as the written language of the country. The species is dioecious, with male and female flowering on separate trees.
Fruits are papery, somewhat twisted, winged structures called samaras that are tan to pink-colored.
Samaras occur in large clusters from September to October of the same year, and may persist on the tree through the following winter. One study reports that an individual tree can produce as many as 325,000 seeds per year. Established trees also produce numerous suckers from the roots and resprout vigorously from cut stumps and root fragments. Elimination of Ailanthus requires diligence, due to its abundant seed production, high seed germination rate, and vegetative reproduction. Followup monitoring and treatment when needed should be an integral part of any serious ailanthus management program.