Persian walnut
Juglans regia
A broad, domed tree with smooth pale grey bark that fissures with age, and stout twigs carrying pinnate leaves of five to nine untoothed leaflets, the end one the largest. The green fleshy husk splits in autumn to release a hard, wrinkled two-halved nut. Introduced to Britain and widely planted; the nuts are picked green in late June for pickling, or ripe from September for the kernel.
Planted and naturalised rather than native, in parks, churchyards, large gardens, hedgerows and railway land, usually on deep, well-drained soil in warm, sheltered lowland sites. Commonest in southern and central England, and spreading where squirrels bury nuts.
The green husk contains juglone, which stains skin and cloth a lasting brown, so wear gloves when handling whole fruit. Walnut is a significant tree-nut allergen. Ripe nuts should be dried before storing, and any kernel that is shrivelled or smells musty discarded, as mould in damp nuts is common. Most trees stand in gardens or on private land, so ask before picking.
Always use more than one reference to confirm a plant. You are responsible for what you choose to forage.
Leaves
Pinnate and alternate on the twig, with five to nine leaflets that have smooth, untoothed margins and a terminal leaflet larger than the rest. Ash leaves are opposite, with more leaflets and finely toothed edges; Tree of Heaven (Ailanthus altissima) has many more leaflets, each with a pair of glandular teeth near the base.
Fruit
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Fruit
Single or paired green drupes about the size of a plum, with a smooth, slightly pitted fleshy husk that blackens and splits irregularly rather than opening along neat seams. Inside is one hard, deeply wrinkled shell in two halves.
Twigs and pith
Twigs are stout with large blunt buds, and a cut made lengthwise shows a pith divided into hollow chambers by thin partitions. A solid, unbroken pith means the twig is not walnut.
Smell and staining
Crushed leaves and green husk give off a sharp resinous scent and leave a yellow-brown stain on the fingers within minutes. The stain darkens over a day and does not wash off, which is the quickest confirmation once fruit is in hand.
Updated 2026-08-07T20:57:55.060Z · Part of the shared Foragers Log catalogue · Fruit