Aspen (Populus tremula) is a deciduous, broadleaf tree known for its habit of ‘quaking’ or ‘trembling’ in the slightest breeze. Indeed, its botanical name ‘tremula’ was given due to its trembling habit, and it’s also known as ‘quaking aspen’. Aspen tree leaves have flattened, flexible leaf stalks, which is how they are able to flutter so easily.
Native to the UK, it’s most common in north-west Scotland, where it’s found in ancient woodland, heaths and riversides. It thrives in full sun and moist soil. Its leaves emerge a coppery brown in spring and then mature to bright green. In autumn they fade to brilliant yellow. Aspens are dioecious, which means their male and female flowers (catkins) grow on different trees.
Aspen makes a fine garden tree although grows to a height of 25m so is best suited to larger gardens. Bear in mind, also, that it has a tendency to send up suckers, which are difficult to remove.
Identifying aspenFrom a distance aspen can be identified by its shimmering foliage in even the slightest breeze. In spring look for coppery foliage and in autumn look for bright yellow (or occasionally red) foliage. On closer inspection, older aspen trees may be covered with lichen, which gives the trunk a black appearance, although the bark is grey and is often marked with diamond-shaped pores, called lenticels. Twigs are slender, dark brown and shiny, and the round leaves have large, irregular, blunt teeth. Look for flattened leaf stalks.
Male catkins are around 12cm long and are brown, turning yellow when ripe with pollen. Female catkins are green. Once pollinated, female catkins develop into fluffy fruits, which release white fluffy seeds in summer.
Aspen trees may be confused with birch trees. Aspen has
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