Aulaga, also known as gorse, furze, or whin, refers to thorny, flowering shrubs in the Ulex genus (pea family, Fabaceae). These evergreen shrubs are resilient and adaptable.
Identifying Aulaga
Aulaga is a dense, bushy evergreen shrub, typically 3-6 feet (1-2m) tall. Its defining feature is rigid, sharp thorns (modified stems and leaves), 0.5-1.5 inches long. Mature plants often have leaves reduced to small scales or spines; young seedlings display trifoliate leaves.
Vibrant, pea-like yellow flowers cluster at thorny branch ends. These blooms, typically 0.6-0.8 inches (1.5-2 cm) long, have a distinct, sweet, coconut-like fragrance. While common gorse (Ulex europaeus) flowers most strongly in spring, some species flower sporadically year-round. After flowering, small, hairy, dark pods develop, each containing 2-6 seeds, ejected when dry.
Where Aulaga Thrives
Aulaga species are native to central and western Europe and the British Isles, with most diversity in the Atlantic Iberian Peninsula. From these native ranges, common gorse (Ulex europaeus) has been introduced globally, often becoming invasive in North America, Australia, New Zealand, and South Africa.
Highly adaptable, this shrub prefers sunny, open areas and thrives in poor, acidic soils. It is common in disturbed sites like coastal heaths, grasslands, roadsides, forest edges, and abandoned farmland. Aulaga tolerates drought and wind. Its nitrogen-fixing ability allows it to colonize and dominate infertile or low-organic content soils.
Ecological Impact and Human Uses
Aulaga offers both ecological benefits and challenges. As a legume, it fixes nitrogen, enriching the soil. Its dense, thorny growth provides shelter and habitat for wildlife, particularly birds, protecting them from predators and weather. Its extensive root system also helps prevent soil erosion, especially on slopes.
When invasive, aulaga negatively impacts ecosystems by outcompeting native vegetation, reducing biodiversity, and forming impenetrable thickets. Its foliage contains flammable oils, making it a significant fire hazard, especially in dry conditions, fueling intense wildfires. Fire heat can also trigger seed germination, leading to rapid re-establishment. Dense infestations can also hinder agricultural and forestry operations.
Historically, aulaga had several human uses, including its high oil content wood as fuel for fires and kilns, burning hot and quickly. It was also processed as animal fodder, despite its thorns, and used as a source for yellow dye. Its dense, spiky nature made it an effective living fence or hedging plant. Its flowers have been used to make wine, tea, or cordials, and the flower buds pickled like capers.
Managing Aulaga
Managing aulaga, especially where invasive, requires a multi-faceted approach. Preventing its spread, particularly through seed dispersal, is an important initial step. Seeds can remain viable in the soil for over 30 years, necessitating long-term management.
Mechanical control methods include cutting, grubbing, or using heavy machinery like mulchers and excavators to remove large infestations. However, aulaga can resprout from cut root crowns, and root fragments can lead to new growth, requiring follow-up. Mowing can suppress growth and prevent seed production, but repeated efforts are needed to deplete root reserves.
Chemical control involves applying herbicides, effective for widespread infestations. Common herbicides include triclopyr, glyphosate, and metsulfuron, often applied after bloom drop for better efficacy. Thorough wetting of the foliage is important for successful application, and specific formulations are available for different site conditions.
Biological control agents, such as the gorse seed weevil (Exapion ulicis), gorse spider mite (Tetranychus lintearius), and gorse thrips (Sericothrips staphylinus), have been introduced in some regions to manage populations. These agents target the plant’s seeds or foliage, reducing its vigor and reproductive capacity. Combining these methods in an integrated management plan often yields the most effective and sustainable results.