Nanjing in East China's Jiangsu province is planning to remove most of its 10,000 poplar trees in an effort to eliminate fallen catkins that bother millions of people in the springtime.

Qi Peiwen, associate counsel for Nanjing Gardening and Greening Bureau, said that the poplar trees will be removed across the city in three years, including downtown and along the freeways.

"The city planted many poplar trees around the year 2000 because they were cheap, grew fast and could improve the environment in a short time," she said. "They can grow very tall in three to five years and begin to shed countless white catkins."

The white catkins, which are a part of poplar tree flowers and seeds, can cause allergic reactions in April and May. Many people across China have to wear masks to avoid breathing in the irritating pollens from poplar, willow and plane trees.

In addition, after growing for 17 years, most of the poplar trees are entering a stage of decline. "Many of their trunks have holes and fragile branches. They may cause casualties downtown if they fall down," Qi said.

Tian Runan, a professor in the gardening and plants department of Nanjing Forestry University, suggested that other kinds of trees, such as ginkgo, cedar, maple and cherry trees, should be planted to replace the poplar trees.