What is the white fur flying everywhere on Nanjing Road? And why is there?

Poplar, alias: Populus tomentosa, Latin scientific name: Populus tomentosa, belonging to Salicaceae and Populus, with white wood and straight texture, can be used as building, furniture, box boards, matchsticks, paper making and other materials, and is the raw material of man-made fibers. Populus tomentosa has good material, fast growth, long life, good drought resistance and salt tolerance, magnificent tree posture and beautiful crown shape, and is an excellent landscaping or street tree that people everywhere like to plant. According to Compendium of Materia Medica, willow catkins have the functions of clearing away heat and toxic materials, benefiting the liver and improving eyesight. However, when the fruits of poplars are about to mature, poplars will fly everywhere when they crack. Poplar trees scattered everywhere in the street will cause environmental pollution and block people's respiratory tract. Therefore, street trees should be planted with male poplars, and female poplars are prohibited. Catkin is the seed of poplar, which makes poplar spread more widely.