Culture
Best grown in rich, humusy, consistently moist, well-drained soils in full sun. This tree thrives in cool northern climates, but will struggle in the heat and humidity of a typical St. Louis summer. Generally intolerant of urban pollutants. In the wild, aspens typically appear in groupings or groves, with all of the stems in a grouping being clones rising from a single extensive underground root system. Large groves featuring hundreds of clones may have all originated from a single stem. Trees are dioecious, so each grouping consists of all male clones or all female clones.
Noteworthy Characteristics
Populus tremula, commonly called European aspen, is native to Europe, Siberia, the Middle East and North Africa. Although alien to North America, an introduced colony of this tree has established itself in the eastern Ozark section of Washington County, Missouri (Steyermark). European aspen is very similar to quaking aspen (Populus tremuloides) of North America except it has a darker trunk color, more coarsely serrate leaves and larger catkins. It is a medium sized deciduous tree that typically grows 30-70’ (less frequently to 90’) tall with an open, rounded crown. Oval to nearly round leaves (to 3” long) are coarsely toothed. Leaves emerge with copper-brown hues, but mature to gray-green. Leaves flutter in even the smallest amount of wind. Leaves turn yellow in fall. Aspens are dioecious, with male and female flowers appearing in separate catkins on separate clones in spring (March-April in St. Louis) before the foliage. Catkins are gray-green and not showy. Small drooping fruiting clusters follow the female flowers.
Genus name comes from the Latin name.
Specific epithet means trembling in reference to the leaves that tremble in a breeze.
Problems
Aspens are susceptible to a large number of disease problems, including dieback, leaf spots, rusts, powdery mildew and cankers. Diseased trees often suffer premature leaf drop as a result thereof. Common insect visitors include caterpillars, borers, aphids and scale. Trees stressed by St. Louis summers are particularly susceptible to diseases such as dieback and to insects such as borers.
Uses
A beautiful tree for cool summer climates. Not recommended for the St. Louis area.