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Fennel
Foeniculum vulgare
A tall aromatic perennial umbellifer with thread-fine, almost hair-like blue-green foliage and flat-topped umbels of small yellow flowers on stout ridged stems, often standing over head height by late summer. Every part smells strongly of aniseed when bruised. Leaves and young shoots are used with fish and in salads, the flower heads for pollen, and the ribbed seeds as a spice; wild plants are the same species as the cultivated bulb form, though they rarely swell a usable bulb.
Naturalised from the Mediterranean and commonest near the sea, on cliff tops, shingle, sea walls and coastal waste ground, and inland on railway banks, roadsides and rough ground on dry sandy or stony soils. Frequent in southern and eastern Britain and coastal Ireland, scarcer northwards.
The plant itself is a well-established food species, though the seeds and concentrated preparations are eaten in small culinary amounts rather than by the handful. The real risk is picking the wrong umbellifer: hemlock (Conium maculatum) has broader, flat, parsley-like leaflets and purple-blotched stems, and smells foul and mousy rather than of aniseed. Hemlock water-dropwort (Oenanthe crocata), which is deadly, grows in wet ground and ditches with flat, coarsely toothed leaflets and a white-flowered umbel, never fennel's thread-fine filaments and yellow flowers. If a crushed leaf does not smell clearly of aniseed, leave it. Sap on skin in bright sun can cause a blistering photosensitive reaction in some people, as with other members of the carrot family, and roadside stands may carry traffic pollution.
Always use more than one reference to confirm a plant. You are responsible for what you choose to forage.
Overall form and flowers
A stout clump of erect stems, often 1.5–2 m tall by August, topped with flat-topped umbels of many tiny yellow flowers without bracts beneath them. Most UK umbellifers of similar size, including hemlock and cow parsley, carry white umbels.
Stem
Solid to hollow, finely ridged, hairless and glossy blue-green with a waxy bloom, swollen and sheathing where each leaf joins. There is no purple spotting or blotching; blotched stems point to hemlock, not fennel.
Leaves
Divided three or four times into thread-fine, almost hair-like segments, giving a soft feathery mass rather than distinct leaflets. Any umbellifer with flat, broad, toothed leaflets is something else.
Smell when crushed
Rub a leaf or crush a stem: a strong sweet aniseed scent, unmistakable and present in every part of the plant. A mousy, rank or parsnip-like smell rules fennel out entirely and should end the picking.
Seeds
Ovoid and strongly ribbed, about 4–8 mm long, greenish at first and drying grey-brown, splitting into two halves. Whole heads can be cut and dried over paper once the umbel browns.
Updated 2026-08-08T07:14:21.099Z · Part of the shared Foragers Log catalogue · Herb