|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.
- "Genus Populus (poplars)". Taxonomy. UniProt. Retrieved 2010-02-04.
- Joint Genome Institute: Populus trichocarpa
- Meikle R.D. 1984. Willows and poplars of Great Britain and Ireland. BSBI Handbook N#4. ISBN 0-901158-07-0.
- Rushforth K. 1999. Trees of Britain and Europe. Collins ISBN 0-00-220013-9.
- Keeler H.L. (1900). Our native trees and how to identify them. New York: Charles Scriber's Sons. pp. 410–412.
- Riparian: along river margins and banks.