Why Rowan Deserves a Closer Look

Rowan (Sorbus aucuparia) is a small native tree that turns up everywhere in Britain — clinging to upland crags, edging Highland lochs, dotting hedgerows and planted along streets. Known to many as the mountain ash, it is not an ash at all, but a member of the rose family. Once you can read its leaves, flowers and berries, you will spot it a hundred yards off, and you will also avoid the handful of native trees that can catch you out.

Leaves: The Giveaway Clues

Rowan leaves are pinnate, meaning each leaf is made up of a row of leaflets arranged along a central stalk. Count them: a typical rowan leaf carries five to eight pairs of leaflets plus a single terminal leaflet at the tip, giving eleven to seventeen in total. The leaflet pairs sit opposite each other along the stalk, and the whole leaf is alternate on the twig — not paired up with another leaf on the opposite side.

Each individual leaflet is narrow and oblong, roughly four to six centimetres long, with a slightly bluish-green upper surface and a paler underside. The detail that matters most is the margin: rowan leaflets are sharply serrated along almost their entire length, with teeth cut right down towards the base. Run a thumb along the edge and it feels distinctly saw-like. In late autumn the leaflets turn a warm russet and gold before dropping, often leaving the bare stalk behind for a week or two.

• Eleven to seventeen leaflets per leaf, including the terminal one
• Teeth running nearly all the way down each leaflet
• Leaves alternate along the twig, not opposite
• Leaflets dull green above, grey-green beneath

Flowers and Summer Signs

From May to June, rowan produces flat-topped clusters — botanists call them corymbs — of small creamy-white, five-petalled flowers. They are dense and frothy, and the scent is sweet but with a slightly sour, almost chemical undertone that some people find off-putting. Bees and hoverflies are fond of it regardless.

Through summer the identification rests on the leaves and the shape of the tree. Rowan is small and slender, rarely more than fifteen metres, with a narrow crown and often more than one trunk rising from the base. Its smooth grey bark carries horizontal breathing pores called lenticels, and the young twigs are grey-brown and slender, with pointed purplish buds that are lightly hairy and never black.

Berries: Autumn's Bright Signal

The berries are unmistakable once you know them. They ripen from late August into September, hanging in heavy, crowded clusters of vivid orange-red to scarlet, occasionally a lighter orange or even yellow in some trees. Each berry is roughly the size of a small pea, and the trick is to look at the base: every rowan berry carries a distinctive five-pointed star-shaped scar left by the fallen flower parts. No other common British berry in those colours has that mark.

Rowan fruit is edible but fiercely sour and astringent raw, thanks to parasorbic acid, which can upset the stomach in quantity. Cooking transforms it into sorbic acid and makes it perfectly safe. Rowan jelly with apple is the classic, and the berries make a superb gin or vodka infusion and a useful addition to hedgerow chutney. If you forage, take only a modest share from abundant trees, pick with the landowner's permission, and never gather from sites where the tree is scarce or protected. The crop is a lifeline for redwings, fieldfares, blackbirds and, in good years, flocks of waxwings.

Rowan in Winter

Once the leaves are gone, look at the buds and bark. Rowan buds are alternate, pointed and purple-brown, often with a dusting of fine hairs, and they sit just above a leaf scar shaped like a small horseshoe. The bark stays smooth and silvery-grey for many years, developing shallow cracks and a darker tone only on old trees. Any lingering berries will have softened and darkened by midwinter, though they often stay on the tree into January if the weather stays mild.

Telling Rowan Apart from Lookalikes

Two trees cause the most confusion. Ash also has pinnate leaves, but its leaves and buds are arranged in opposite pairs, its leaflets are toothed only towards the tip and smooth near the base, and its buds are jet black. Ash carries winged keys, not berries. Elder has opposite pinnate leaves and flat creamy flower heads, but its berries are dark purple-black and its twigs are filled with soft pith.

Among the other native Sorbus species, whitebeam has simple, lobed-edged leaves that are strikingly white and felted underneath, while wild service tree has simple, maple-like lobed leaves and brown, spotted berries. If you find pinnate leaves, saw-edged leaflets, purple buds and star-based scarlet berries on the same tree, you have rowan — and a very fine tree to know.