Aspen trees are slender and graceful, airy and light, with pale bark. Round, wavy-edged leaves move with the slightest breeze.
It’s rare to be able to identify a tree by sound, rather than sight, but the distinctive, trembling, rustling leaves of the European aspen tree (Populus tremula) are a giveaway, lending the aspen one of its common names: the quaking tree.
While ancient oaks are celebrated and venerable yew trees grace many of our churchyards, the aspen is little known and often overlooked in Britain. Yet the aspen has much deeper roots in our landscape’s history.
Learn more about the fascinating aspen in our expert guide, including how to identify and where to see.
How to identify aspen trees
Height: Up to 20 metres
Tree shape: Slender, spreading
Bark: Smooth, grey with horizontal lines
Leaves: Nearly round, wavy edges, a little paler on underside, trembles in any breeze, vary in size from 2.5cm to 6cm across; leaves are more heart-shaped on sucker shoots. Leaf stalks long and flattened. Leaves turn to clear yellow or red in autumn.
Catkins: Flower between February and April, look like caterpillars. Male catkins are 5–10cm long with pink-red anthers and grey silky hairs. Female catkins are 2–6cm, grey-greenish and silky. Find out more in our guide to how to identify catkins.
Fruits: Fruiting catkins reach 10–12cm, ripening in May with white woolly seeds for wind dispersal.
History of the aspen tree
About 12,000 years ago, as Ice Age glaciers retreated, trees gradually moved north from warmer lands to colonise the British Isles. Pollen records show that our earliest trees were birch, willow – and aspen. Pine, hazel, oak and alder followed later, and trees such as lime, elm, holly and ash, beech and hornbeam took even longer to arrive. Since that time, aspen has gradually migrated northward in our warming climate.
Aspen trees distribution
Today aspen grows across Europe and Asia in cooler, temperate regions, retreating to the mountains to the south of its range. Aspen is found throughout the British Isles in woodlands and heathlands, and even on rocky coasts, but only the north and west of Scotland can boast aspen in significant numbers. In the cool Scottish autumn, the clear golden-yellow leaves of aspen trees are a natural wonder.
Aspen tree habitat
Aspen can tolerate a wide range of soils and climatic conditions, preferring full sunlight and well-draining, moist soils that are not waterlogged. Many other species use the aspen tree. Its leaves are a food plant for the rare dark-bordered beauty moth; the aspen hoverfly uses decaying aspen wood to lay its eggs; aspen bracket fungus depends on it.
Aspen tree life cycle
So why is this beautiful tree so scarce? Aspen trees don’t usually exceed 100 years old. Aspen is dioecious, with separate male and female trees, and they rarely flower. But that’s only part of the story – the tree’s mystery lies under the soil.
Instead of using flowers, aspen trees tend to propagate by suckering underground. The roots and suckers travel through the soil for up to 40 metres. One small tree can rapidly become a small aspen grove, forming a ‘clone’ of connected trees that are all part of the same single organism. Clones live much longer than an individual tree above ground. Studies of the closely related North American aspen (Populus tremuloides) have identified one clonal colony, called Pando, that weighs six million kilograms, covers more than 40 hectares (or 56 football pitches) and is estimated to be more than 10,000 years old; it is among the world’s oldest living organisms. This incredible longevity could be why our own European aspens rarely flower – the individual clones might be too old.
Management and threats to aspen trees
In spite of its relative scarcity, delicate aspect and shivering leaves, aspen is a tough tree. Its suckering habit means it is difficult to clear aspen from an area of ground once established, and it regenerates well after fire. Damage or cutting simply doubles aspen’s determination to grow. Its leaves attract nibbling cattle, sheep and deer, and it is a favourite food of the European beaver. Some ecologists are worried about the implications of beaver reintroduction for the aspen. The Trees for Life project in the Scottish Highlands has a simple solution to this gnawing problem: more aspen trees!
Trees similar to aspen
Aspen is part of a wider family of poplar trees, and one of only two native poplars in the British Isles. The other is the uncommon black poplar (Populus nigra ssp. betulifolia), a gnarled, drooping, much-loved tree that graces hedges and fields across lowland England and Wales with its distinctive red catkins.
Several other poplar species are naturalised and widespread in the British Isles. The hybrid black poplar (Populus canadensis) is often planted on roadsides. The white poplar (Populus alba) was probably introduced from southern Europe in medieval times; together with the grey poplar (Populus canescens), it is used in landscaping. The pointed, controversial Lombardy poplar (Populus nigra subsp. italica) was introduced from northern Italy in 1758.
Poplar tree folklore, mythology and symbolism
Poplars were sacred to many early people. Golden crowns of poplar leaves have been found in burial mounds in Mesopotamia dated to 3,000BC. In Roman mythology, Hercules bound his head with poplar leaves after battle, to show he could walk between the worlds of the dead and the living.
Similar themes occurred in ancient Ireland. The magical Ulster hero Cuchulain carried a shield of aspen that protected him from fear. For the Celts, aspen was a ‘stick of woe’ – a sign that the otherworld was near. Stories of the Fianna, the mythical Irish band of warriors, tell of Oscar son of Oisin near death and trembling “like leaves in a strong wind, or like an aspen tree that is falling”. In pre-Christian Ireland, aspen wands were buried with heroes as a reminder that death was not the end for the soul.
Christianity also linked aspen with death: the tree’s wood was said to have made Christ’s cross. Another story says aspen was punished to shudder for eternity, as the only tree that would not bow down to Jesus as he travelled to Calvary. In the Scottish Highlands, aspen is avoided for midsummer fires, and farming and fishing implements should not be made from it.
Unsurprisingly for such a noisy tree, aspen folklore relates to air and communication. An aspen leaf under the tongue bestows eloquence, usually a gift from the faery queen. In the Ogham, the ancient Irish tree alphabet, whispering aspen is commaín carat: ‘the exchange of friends’.
Next time you see an aspen tree – whether you are admiring its fresh green rustling leaves in the springtime or cheered by the golden yellow of aspen’s autumn foliage – you might want to whisper in return: “I know your story.”
Words: Lisa Schneidau has worked in British nature conservation for more than 20 years. A professional storyteller and the author of Woodland Folk Tales of Britain and Ireland, she lives on Dartmoor. lisaschneidau.co.uk