Why learn to read bark?

Woodland in winter can feel like a closed book. The leaves are gone, the flowers are months away, and the canopy that gave everything away in June has turned into a tangle of bare twigs. Yet this is exactly the season when trees become most individual. Without foliage to distract you, bark, buds and the shape of the branches do all the talking.

Once you can tell an ash from an oak from a birch at twenty paces in January, every walk changes. You begin to notice which trees stand where, how the woodland is put together, and which species are thriving on your patch. You also start to read a tree's history in its surface: the fissures, the lichens, the scars of old branches and the peeling ribbons of bark that make birch woods glow on a grey afternoon.

Use three clues at once, not one

Bark alone can mislead you. A young oak can look as smooth as a beech, and a shaded ash can be furred with algae until it seems almost green. The trick is to gather several clues and let them confirm one another.

• Bark texture and colour: smooth, cracked, fissured or peeling; grey, brown, cream, or green with algae.
• Buds: their size, colour, and whether they sit in opposite pairs or alternate along the twig.
• Branching pattern: opposite or alternate, and the overall outline of the tree against a winter sky.

Get into the habit of looking up for the silhouette, then down at a low twig, and finish with the trunk itself. The three views usually agree.

Oak: fissures, plates and a craggy outline

A mature English oak is unmistakable. Its bark is deeply fissured into broad, vertical plates, often hard to the touch and dull grey-brown, with a dusting of moss and lichen in damp woodland. The ridges are chunky rather than fine, and they twist and branch as they run up the trunk. Pedunculate oak tends to be the more gnarled and contorted of our two native oaks, with heavy limbs and a wide, streaming crown; sessile oak, more at home on upland and acidic soils, often grows straighter with an even more deeply ridged bark.

Young oaks are a different matter altogether: pale grey and smooth, sometimes faintly green with algae, and only beginning to crack in their twenties. Look then at the buds. Oak buds are brown, scaly and clustered in a little crowd at the end of the twig, with smaller ones spiralling below. Oak, ash and most of our broadleaves are spirally arranged rather than opposite.

Ash: pale ridges and velvety black buds

Ash bark is a soft, pale grey that can look almost silvery in winter light, and on a young tree it stays smooth for a long time. In middle age it develops a distinctive pattern of shallow, wavy ridges that cross one another, forming a loose diamond or net-like texture down the trunk. It rarely achieves the deep, blocky fissures of an old oak, and it is often mottled with pale green algae and orange-brown lichens.

The clincher is the buds. Ash has opposite buds: pairs sit level with one another on either side of the twig, topped by a single terminal bud, and they are jet black and velvety soft, like tiny velvet buttons. Very few of our native broadleaves are opposite, so this one feature rules out most of the woodland around it. Given the toll ash dieback is taking, being able to pick out ash at any time of year has become genuinely useful for anyone who walks or gardens with trees.

Birch: paper, diamonds and peeling ribbons

Birch bark is in a class of its own: thin, papery and peeling in horizontal strips, with a surface that feels like stiff card. Silver birch is the familiar one, its bark turning creamy white as it matures, marked with dark horizontal lines called lenticels and, at the point where large branches have been shed, rough black diamonds that break up the white like a pattern of scars. The twigs are slender, drooping and noticeably wispy at the tips.

Downy birch is more likely in wet or peaty soils and higher ground. Its bark is greyer and duller, less prone to peeling into clean white scrolls, and its twigs and young shoots are softly hairy rather than smooth. Young birches of both species start out reddish-brown before they whiten, which catches people out on heathland edges. Please admire the peeling bark with your eyes only: stripping it from a living tree leaves a wound and removes habitat for insects and lichens.

Practising in the field and at home

Choose three trees near your home and visit the same ones through the year, sketching or photographing the trunk and a twig with buds. Compare an old oak and a young one and the difference will bed in fast. In the field, carry a hand lens for bud detail, and look at trees from a distance as well as close up. Above all, take a moment at the base of the trunk, where mosses, liverworts and lichens gather and where many invertebrates spend the winter.

In the garden, bark becomes a design tool. A birch planted where low winter sun catches it will light up the whole border, while an oak sapling is a long-term gift to wildlife, supporting hundreds of species of moths and insects. Even a modest garden can hold a tree whose winter face is worth waiting for. Learn its bark, and you will never see an empty landscape again.