Ulex europaeus | Gorse

Introduction

Gorse (Ulex europaeus) is the fiercely spiny evergreen shrub that covers heaths, cliffs, and rough ground in sheets of brilliant yellow, famously flowering in every month of the year. Its coconut-scented blossoms and impenetrable thickets are a landmark of Atlantic Europe, where the plant both shelters wildlife and signals poor, acidic land. Tough, flammable, and nearly impossible to walk through, it is one of the most characterful shrubs of the western European countryside.

Taxonomy

Ulex europaeus is a legume in the family Fabaceae, the pea and bean family, and belongs to the tribe Genisteae alongside brooms. Its leaves are reduced to spines and its stems take over the work of food production. Like all green plants it depends on Photosynthesis, and its green, ridged stems run that process year-round, which is what allows a shrub in a windswept, winter-wet climate to keep growing when most of its neighbours are bare.

Physical Characteristics

Gorse is a dense, much-branched evergreen shrub usually one to two metres tall, occasionally reaching three. Its leaves are modified into stiff, sharp green spines one to three centimetres long, borne in the leaf axils, and the young stems are green, ridged, and hairy and end in a spine. The pea-like flowers are bright golden yellow, about one and a half centimetres across, with a coconut-vanilla scent, and are carried in such numbers that the whole plant appears to be a mass of flower. The seed pods are small, hairy, and black, and they split explosively in hot weather with an audible crack.

Habitat

It grows on heathland, moorland, coastal cliffs, rough pasture, road verges, and railway embankments, especially on dry, acidic, nutrient-poor soils. It is native to western Europe from Norway and Britain south to Portugal and has been introduced—often becoming invasive—to New Zealand, Australia, Chile, the west coast of North America, and South Africa. It needs full light and cannot tolerate shade, and it thrives where grazing and fire keep competing scrub back.

Diet

Gorse feeds itself by photosynthesis, carried out mainly in the green stems and spines rather than in true leaves, which are almost absent. As a legume it also has a decisive advantage: nodules on its roots host bacteria that fix nitrogen from the air, giving it access to a nutrient that is scarce in the acidic soils it favours. This is why gorse thrives on ground that starves most other shrubs.

Reproduction

The flowers are pollinated by bees, which are drawn by the strong scent and are dusted with pollen when they push into the keel. Because gorse flowers through most of the year, it is a valuable nectar source in winter. Seeds ripen in hairy pods that dry, twist, and burst, flinging seeds several metres from the parent. The seeds are hard-coated and can lie dormant in the soil for decades, germinating in bulk after fire or soil disturbance.

Conservation

In its native range gorse is abundant and not threatened, and where it is carefully managed it is valued for the rare birds—such as Dartford warbler and stonechat—that nest in its dense cover. Outside that range it is a serious invasive weed: in New Zealand and Chile it forms impenetrable stands on farmland and is controlled by clearance, grazing, and biological agents. Its extreme flammability also makes it a fire hazard wherever it builds up.

Fun Facts

• The old saying is that “when gorse is out of bloom, kissing is out of fashion”—it flowers almost all year.
• Its flowers smell strongly of coconut, especially on warm days.
• Seed pods burst with an audible pop on hot summer days, throwing seeds metres away.
• The whole shrub is fiercely spiny, and the spines are modified leaves.
• Because it fixes its own nitrogen, it thrives on soils too poor for most shrubs.