The male catkins are patterned green and brown, 5–10 centimetres (2.0–3.9 in) long when shedding pollen; the female catkins are green, 2–6 centimetres (0.79–2.36 in) long at pollination, maturing in early summer to bear 10–20 (50–80) capsules each containing numerous tiny seeds embedded in downy fluff.

[5][6] This often makes the job of clearing unwanted trees from an area especially difficult, as new suckers will continue to sprout from the extensive root system for up to several years after all surface growth has been eliminated.

[citation needed] The species is native to Europe and Asia, from Iceland[7] and the British Isles[8] east to Kamchatka, north to inside the Arctic Circle in Scandinavia and northern Russia, and south to central Spain, Turkey, the Tian Shan, North Korea, and northern Japan.

[6][9] Eurasian aspen is a water and light demanding species that is able to vigorously colonize an open area after fire, clear cutting or other kinds of damage.

[citation needed] Aspen is resistant to browsing pressure by fallow deer owing to its unpleasant taste.

[12] The fastigiate cultivar 'Erecta', with bright yellow autumn colouring, has gained the Royal Horticultural Society's Award of Garden Merit.

Given its hardiness and capacity for rapid growth and regeneration, it plays an important role in the production of wood for renewable energy.