Identify a tree by its leaf

Leaves are the part of a tree you can almost always reach, and they are on the tree for most of the year. They are less distinctive than flowers or fruit, but a careful look at a few features goes a long way. Use the identifier for a shortlist, then use these features to decide between the candidates, or to check that the top match makes sense.

How to photograph a leaf

• Pick a mature, undamaged leaf from the outer part of the canopy. Avoid the soft new flush at branch tips.
• Lay it flat on paper or hold it against the sky. Shoot from directly above, with the tip, base and stalk all in the frame.
• For compound leaves, photograph the whole leaf, from the base of its main stalk to the last leaflet.
• Take a second shot of the underside if it looks different: paler, hairy, scaly or silvery.

The leaf checklist

1. Arrangement on the twig

Alternate leaves (one per node, staggered) are the most common. Opposite leaves (two per node, facing each other) narrow things a lot. In temperate regions, a well-known shortcut is that most large opposite-leaved trees are maples, ashes, dogwoods or horse chestnuts. Among tropical fruit trees, opposite leaves point to guava and its relatives, or to mangosteen. Whorled leaves (three or more per node) are rarer still.

2. Simple or compound

A simple leaf has one blade. A compound leaf has several leaflets on one stalk: pinnate (leaflets along a central stalk, like ash, walnut or lychee), palmate (leaflets radiating from one point, like horse chestnut or white sapote), bipinnate (leaflets themselves divided, like many acacias), or with three leaflets (like santol). Very fine, feathery leaves made of many small leaflets are typical of the pea family, such as tamarind.

3. Overall shape

Common shapes are oval, egg-shaped (widest below the middle), lance-shaped (long and narrow, like mango), heart-shaped, and lobed (oak, maple, fig, breadfruit). Conifers have needles or tiny scales instead of broad leaves.

4. The edge

Is the margin smooth (entire), finely toothed, coarsely toothed, or wavy? Many fruit trees in the rose family, such as apple and cherry, are finely toothed; most tropical evergreen fruit trees are smooth-edged, like mango, while citrus ranges from smooth to finely toothed.

5. Vein pattern

Pinnate veins branch off one central midrib. Palmate veins spread from the base, like maple. Some leaves have three strong veins from the base, a feature of jujube. Parallel veins, running the length of the leaf, mark monocots such as palms, bananas and grasses rather than broadleaf trees.

6. Surface and underside

Glossy or matte, smooth or hairy, and is the underside a different colour? Some trees are recognisable from the underside alone: star apple is golden-brown and silky beneath, and durian is coppery to silvery and scaly.

7. Smell

Crush a leaf and smell it. Citrus, bay, eucalyptus, guava and mango each have a strong, characteristic smell; many other trees have none.

8. Sap and the leaf stalk

Milky sap from a torn leaf or stalk points to a short list of families, including figs and mulberries, jackfruit, and the sapote family. Look at the stalk too: a winged stalk is a citrus trait, extreme in kaffir lime, and a winged central stalk between leaflets marks ice cream bean.

Classic look-alikes

• Maple and sycamore (plane): both have palmately lobed leaves, but maple leaves are opposite and plane leaves are alternate, and plane bark flakes off in patches.
• Ash and walnut: both pinnately compound, but ash is opposite and walnut alternate, and crushed walnut leaves have a strong smell.
• Pine, spruce and fir: pine needles come in bundles of two to five; spruce needles are single, stiff and sharp; fir needles are single, flat, soft, and usually have two pale lines underneath.
• Mango and avocado: both large, smooth-edged and leathery; see the tropical fruit tree identifier.