Salix caprea Seeds | Goat Willow

Goat Willow (Salix caprea) seed — Goat Willow (*Salix caprea*): native to Europe from the British Isles and southern Scandinavia east across Russia and Siberia, with outposts in Asia Minor and the Caucasus; introduced and naturalised in North America.

LATIN NAME: Salix caprea

COMMON NAME: Goat Willow

Plant Profile

Salix caprea is a shrub or small tree, often branching low into a broad, rounded shape, with grey-green leaves that are broadly oval, wrinkled above and felted grey beneath. The margins are wavy rather than finely saw-toothed, and vigorous shoots carry large, kidney-shaped stipules at the base of the leaf stalk, a good character for telling goat willow from its relatives. The bark is smooth and olive-grey on young wood and becomes fissured with age.

Goat willow is dioecious: male and female catkins sit on separate trees, and only the male ones turn gold. The female catkins are longer, greener and less showy, and they ripen into capsules that release tiny seed in a parcel of white down. Because flowering happens before the leaves open, wind has a clear run at the pollen, and insects have an unobstructed landing strip.

The old country name for the tree is sallow, and it survives in the names of the spring moths whose caterpillars feed on it. The purple emperor is the best-known case: this large woodland butterfly lays its eggs on goat willow foliage, and the caterpillars that hatch live on the leaves. Several noctuid moths of early spring depend on the same catkins.

Goat willow is a coloniser. It arrives on disturbed ground, in wet ditches, on spoil and in burnt woodland, grows fast, and dies young, and its shade shelters the slower trees that will replace it. In a garden that makes it useful for filling a wet corner quickly, and awkward if you want a tidy boundary.

Science & Biotechnology

Salicin was isolated from willow bark by the German pharmacist Johann Andreas Buchner in 1828, and chemists spent the rest of the century working out how to make the active principle in a bottle. Acetylsalicylic acid was synthesised at Bayer at the end of the nineteenth century, and the world’s most familiar painkiller is a modified willow compound with a name borrowed from another plant.

Willows root from cuttings with a readiness few trees match, and that made them the base of short-rotation coppice for biomass. The same fast growth and deep-rooting habit have been turned to phytoremediation: willow stands take up cadmium and other metals from contaminated land, and the harvested wood concentrates what the soil held. The poplar was the first tree to have its genome sequenced, and willow genomes have followed into biomass breeding programmes.

Uses & Benefits

A queen bumblebee emerging from hibernation in early spring has almost nothing else to feed on. Sallow catkins supply both pollen and nectar, and a stand of goat willow in a hedge is one of the most valuable early resources a garden can hold. Honeybees work the catkins too when the weather allows flight.

The bark contains salicin, a phenolic glycoside that the body converts into salicylic acid, along with the related compounds salicortin and tremulacin. Willow bark was the standard European remedy for pain and fever for centuries, and the goat willow was one of the species gathered for it. The compound is a genuine piece of pharmacology rather than a folk claim.

Growing from Seed

Unlike the osiers grown for baskets, goat willow strikes poorly from hardwood cuttings, and the standard advice to push a willow stick into the ground does not work reliably here. Layering is dependable, and seed is easy if it is fresh, because willow seed loses its power to sprout within a very short time of shedding. Surface-sow onto damp compost in a closed frame, keep it out of direct sun, and prick the seedlings out as soon as they are large enough to handle.

The seed needs light and constant moisture, so cover it with the barest dusting of compost and mist twice a day. Grow the seedlings on in pots until they stand 30 cm, then plant out into damp ground at 2 to 3 m. Coppice or pollard the tree on a short rotation to keep the catkins within reach and the wood young.

Our Take

If you plant goat willow, plant it for the bees and the moths rather than for the shape of the tree. A few wet corners of the garden are enough, and the blueberry willow will give you catkins on a plant that never needs a ladder, while the Euphrates poplar shows the same family doing pioneer work on dry ground. Green alder is another early colonist worth mixing in.

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