Two species of poplars, the European Aspen (Populus tremula) and Black cottonwood (Populus trichocarpa), are common poplars in the Northern Hemisphere. Both species have light grey and smooth young stems, while the trunk of older trees is darker and more fissured. Black Cottonwood is typically larger than European Aspen and has narrower leaves.
The European Aspen grows all over Europe, is widespread across Asia, and even occurs in North Africa. European Aspen is distributed throughout Britain in different types of woodland. It is particularly common in the Scottish Highlands and Islands where it occurs in diverse habitat ranging from sea cliffs up to upper forest limits. Similarly, European Aspen is common in Scandinavia, from southern Norway to northern Lapland. This species most often grows in mixed stands in Scandinavia, but in dense stands of its own in southern Norway. European Aspen is very rare here in Iceland, it occurs in the wild in Icelandic woodlands and heaths and is considered a native woody plant in Iceland. It is a small tree or shrub here, and has the distinctive broad, round-shaped leaves.
Black Cottonwood is native to the west coast of North America, where it often grown in damp riparian habitats and may reach up to two hundred years. Black Cottonwood is an introduced tree here in Iceland and has been planted all over the country. This tree is quite common in South West Iceland as a component of shelter belts on traffic islands, surrounding agricultural lands, and is quite common in Reykjavik city. Black Cottonwood grows well here forming strong erect trees, with long often upright branches. It produces massive amounts of pollen in the spring and early summer. Black Cottonwood is very popular in tree plantations in Iceland.
This time of year, the winter sun warms the leafless poplars that are favourite places for overwintering passerine birds, such as groups of Starlings (Sturnus vulgaris) and the occasional Redwing (Turdus iliacus).