|Foliage of Populus tremula|
The flowers are mostly dioecious (rarely monoecious) and appear in early spring before the leaves. They are borne in long, drooping catkins. The male flowers have a group of 4–60 stamens on a disk. The female flower is a single-celled ovary in a cup-shaped disk.
Pollination is by wind. The fruit is a two to four-valved capsule, green to reddish-brown, mature in mid summer. It contains tiny light brown seeds surrounded by tufts of long, soft, white hairs which help wind dispersal.
Poplars and aspens are important food plants for the larvae of a large number of Lepidoptera species. Pleurotus populinus, the aspen oyster mushroom, is found exclusively on dead wood of Populus trees in North America.
Populus Facts for Kids. Kiddle Encyclopedia.