Start with the leaf in your hand

By late April the hedgerows and woodlands have filled out, and from then until the first gales of autumn a walker can name most of the trees along a footpath without looking up. Leaves are far easier to read than bark or silhouette, and four species in particular — oak, ash, beech and hawthorn — turn up again and again, from ancient woodland to roadside hedge. Learn these four and the British countryside becomes noticeably more legible.

Before you begin, note three things about any leaf you pick. First, is it simple (a single blade) or compound (several leaflets on one stalk)? Second, how are the leaves arranged on the twig — in opposite pairs, or alternately? Third, look at the margin: is the edge smooth, toothed, or lobed? Get into the habit of turning the leaf over, too; the underside often settles an argument.

Oak: rounded lobes and clustered leaves

The oak is the easiest of the four to recognise at a glance. Its leaf is deeply lobed, with rounded, finger-like lobes and smooth margins between them — no bristles, no sharp points. A red oak from a park or garden will have bristle-tipped lobes, but our native oaks never do.

Look closer, and you can separate the two common species:

• Pedunculate oak (Quercus robur): leaves have almost no stalk, with a pair of small ear-like lobes at the base clasping the twig. The leaves crowd towards the ends of the shoots.
• Sessile oak (Quercus petraea): leaves have a clear stalk of 1–2.5 cm, and the lobes are more regularly spaced. This is the oak of the wetter west and north.

Oak leaves open late, rarely fully out before early May, and hang on the tree through the summer with a leathery, dark green look.

Ash: opposite, pinnate, and late

Ash is the odd one out among our common trees: its leaves are compound, made up of seven to thirteen leaflets arranged in opposite pairs along a central stalk, with a single terminal leaflet at the end. Each leaflet is long, narrow and pointed, with a toothed margin, and the whole leaf can reach 30 cm.

Two details confirm it. First, ash leaves are opposite on the twig — a rarity among British trees, shared mainly with field maple, sycamore and horse chestnut. Second, ash is famously late to leaf and quick to drop; if a tree is still bare in mid-May while the oaks around it are in full leaf, it may well be ash. The black velvety buds, shaped like small hooves, are unmistakable in winter.

Beech: oval, silky, and glossy

Beech leaves are simple, oval in shape, 5–10 cm long, with a wavy, softly hairy margin rather than sharply cut lobes. Young leaves in April emerge silky and pale green, sometimes with a coppery flush; mature leaves are dark, glossy and smooth on top and a lighter green beneath.

The leaf edges carry fine silky hairs, especially when young — run a finger along a leaf edge and it feels soft rather than crisp. In shape, beech is one of the neatest and most symmetrical of our leaves, held almost in a fan along the shoot.

Alone in a wood, beech is easy. In a hedge, though, it is often confused with hornbeam. Hornbeam leaves are also oval and strongly ribbed, but the margin is double-toothed (each vein ends in a tooth with smaller teeth between) and the leaf base is distinctly heart-shaped. Hornbeam leaves also turn yellow early and cling to the hedge far longer than beech.

Hawthorn: small, lobed, and everywhere

Hawthorn is the hedgerow tree. Its leaves are small — usually 2–5 cm — and deeply cut into three to five lobes, with toothed edges and a wedge-shaped base. They appear on short spur shoots, often in dense clusters, giving hawthorn a fresh, bright green look in May when the whole hedge breaks into white blossom.

The lobes reach perhaps halfway to the midrib, which distinguishes hawthorn from blackthorn. Blackthorn leaves are not lobed at all: they are oval, finely toothed and pointed, and they open in March, weeks before hawthorn. If a hedge is white in March, that is blackthorn; white in May, hawthorn. In older woodland you may also meet Midland hawthorn, whose lobes are shallower and less deeply cut.

Sorting the lookalikes

Four comparisons worth carrying in your head:

• Oak vs most other trees: rounded lobes, no bristles, often clustered at the shoot's tip.
• Ash vs rowan: ash leaflets sit in opposite pairs with a single terminal leaflet; rowan leaflets are more numerous, sharply toothed almost to the midrib, and the whole leaf looks fern-like.
• Beech vs hornbeam: beech is wavy-edged and soft; hornbeam is doubly toothed with a heart-shaped base.
• Hawthorn vs blackthorn: hawthorn is lobed and later; blackthorn is oval and earlier.

Nothing replaces handling a leaf, though. Take a walk in May or June with a pocket guide, pick up a fallen leaf from the path rather than tearing one from the tree, and check the edge, the base and the underside. Do it often enough on the same stretch of lane and you will begin to know the hedge by name: the pedunculate oak leaning out over the gate, the ash behind it, the beech hedge further on, and hawthorn all the way down the verge.