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   Ulex europaeus (tree, shrub)  français     
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      Photo: Staff CDFA, California Dept. of Food & Agriculture, 
Integrated Pest Control Branch. © 2001 CDFA - Click for full size   Infestation of Ulex europaeus at Dunedin, New Zealand (Photo: Colin Wilson) - Click for full size   Infestation of Ulex europaeus on the Banks Peninsula, New Zealand (Photo: Colin Wilson) - Click for full size   Flowers of Ulex europaeus on the Banks Peninsula, New Zealand (Photo: Colin Wilson) - Click for full size   Photo: Sherry Ballard © California Academy of Sciences - Click for full size   Photo: Staff CDFA, California Dept. of Food & Agriculture, 
Integrated Pest Control Branch. © 2001 CDFA - Click for full size   Photo: J.P.Clark, California Dept. of Food & Agriculture, Integrated Pest Control 
Branch. © 2001 CDFA - Click for full size
    Taxonomic name: Ulex europaeus L.
    Synonyms:
    Common names: ajonc (French), ajonc d'Europe (French), bois jonc (French), chacay (Brazil), furze (English), Gaspeldoorn (Dutch), genêt (French-Reunion (La Réunion)), Ginestra spinosa (Italian), gorse (English), jonc marin (French), kolcolist zachodni (Poland), picapica (Brazil), Stechginster (German), Tojo (Spanish), vigneau (French), vIrish furze, whin (English), zépinard des hauts (French-Reunion (La Réunion))
    Organism type: tree, shrub
    Ulex europaeus is a spiny, perennial, evergreen shrub that grows in dense and impenetrable thickets which exclude grazing animals. It is common in disturbed areas, grasslands, shrublands, forest margins, coastal habitats and waste places. Ulex europaeus is a very successful and tenacious plant once it becomes established and is extremely competitive, displacing cultivated and native plants, and altering soil conditions by fixing nitrogen and acidifying the soil. It creates an extreme fire hazard due to abundant dead material and its oily, highly flammable foliage and seeds. Soil is often bare between individual plants, which increases erosion on steep slopes where Ulex europaeus has replaced grasses or forbs. Spiny and mostly unpalatable when mature, Ulex europaeus reduces pasture quality where it invades rangeland. Ulex europaeus understorey in cultivated forests interferes with operations; increasing pruning and thinning costs and can interfere with the growth of conifer seedlings.
    Description
    Many-branched shrubs to 6-20 dm tall; young branches usually terminating in a spine, younger parts somewhat glaucous, and hirsute to tomentose. Phyllodes 4-14mm long, usually spine-tipped. Calyx yellow, 12-16 (-20)mm long, densely villous, persistent; corolla yellow, 15-20mm long. Pods 11-20mm long, 6-8mm wide, slightly compressed, densely villous. Seeds 1-4, brownish green, reniform." (Wagner et al., 1999. In PIER, 2002)
    Similar Species
    Ulex minor

    More
    Occurs in:
    agricultural areas, coastland, natural forests, planted forests, range/grasslands, ruderal/disturbed, scrub/shrublands, water courses, wetlands
    Habitat description
    The ability of gorse to fix nitrogen enables this plant to colonize and dominate areas with poor soils. Gorse plants extract and retain plant nutrients such as calcium, magnesium, and sodium, which changes nutrient dynamics and can impoverish the soil (IPM, 2000). The geographical distribution of gorse depends primarily on temperature. It cannot survive in arid climates, or in continental regions where there are extremes of heat and cold. Day length may also affect its latitudinal distribution, as short-day conditions inhibit maturation and prevent thorn formation and flowering (IPM, 2000). Gorse will grow on most soil types, including acidic soils with less than 4% organic content (Zabkiewicz 1976; Hoshovsky 1986. In IPM, 2000).

    Gorse grows well in shady slopes with high soil moisture and good drainage. Look for gorse in areas with degraded soils or disturbed sites such as roadsides, pasture lands, gravelly floodplains, cleared forests, or other areas following a disturbance (Cook 1987; Zielke et al. 1992. In IPM, 2000).

    In Hawai‘i, naturalized in open areas and along roadsides, 760-2,000 m, forming dense, monotypic thickets. (PIER)
    General impacts
    Ulex europaeusis is a major weed in five countries (R. Hill, pers. Comm.). It is extremely competitive, displaces cultivated and native plants, and alters soil conditions by fixing nitrogen and acidifying the soil (Egunjobi, 1969; Grubb and Suter, 1970). It creates an extreme fire hazard due to its oily, highly flammable foliage and seeds, and abundant dead material. It not only increases the risk of fire, but also produces a hotter fire than most weeds (MacCarter and Gaynor 1980, In IPM, 2000). This fire risk increase threats on the margins of native vegetation (R. Hill, pers. Comm.).

    Because of various characteristics of the plant, the soil is often bare between individual gorse plants, which increases erosion on steep slopes where gorse has replaced grasses or forbs. Spiny and mostly unpalatable when mature, gorse reduces pasture quality where it invades rangeland. Gorse understory in forests interferes with cultural operations, increasing pruning and thinning costs (Balneaves and Zabkiewicz 1981. In IPM, 2000), and can interfere with the growth of conifer seedlings (Clements et al., 2001). It excludes grazing animals from rangelands and pasture (Richardson and Hill, 1998; Tulang, 1992).
    Uses
    Introduced from Western Europe as an ornamental or hedge shrub (CDFA). It has potential for land reclamation and has been used as a hedge plant and for binding soil on dry sandy banks. On marginal land it is a source of food for cattle and ponies and formerly, after removal of spines, it was used for fodder (Binggeli, 1997). It is used as an ornamental shrub, hedge plant, pollen (for New Zealand bees), medicinally, flowers for dye particularly for easter eggs, formerly as fuel, food for livestock and windbreaks (Blood, Kate. pers.comm. 12 January 2001). Lectins extracted from seeds will bind selectively to certain glycoproteins and glycoplipids, and are widely used in tissue typing (Audette et al., 2000). It sometimes acts as a nurse crop for native regeneration (Hackwell, 1980), but sometimes not (Lee et al., 1986).
    Notes
    The geographical distribution of gorse depends primarily on temperature. It cannot survive in arid climates, or in continental regions where there are extremes of heat and cold. Day length may also affect its latitudinal distribution, as short-day conditions inhibit maturation and prevent thorn formation and flowering. (IPM, 2000)

    Gorse is a successful invasive species because it can: (1) fix nitrogen; (2) acidify and (at least temporarily) impoverish soils by taking up bases; (3) survive on a variety of soil types; (4) produce copious amounts of heat-tolerant seeds with long-term viability; and (5) regenerate rapidly from seeds and stumps after disturbances such as brush clearing or fires. (Hoshovsky, 1989)
    Geographical range
    Native range: The western seaboard of Europe and Great Britain and Ireland, and possibly Italy. Natural limits near Portugal in the south and the Netherlands/Denmark in the north (R. Hill, pers. comm.). Naturalized in Norway, Sweden, Poland (Holm et al., 1997) and Switzerland. Its indigenous status in Italy, central Europe, and localised montane districts of North Africa is uncertain (R. Hill, pers. comm.).
    Known introduced range: Costa Rica, Haiti, Jamaica, Panama, Trinidad and Tobago, Argentina, Falkland Islands, Chile, Brazil, Colombia, Bolivia, Ecuador, Uruguay, India, Sri Lanka, Turkey, Algeria, South Africa, Tanzania, St Helena (ILDIS), Hawai‘i, Australia, Canada, China, Indonesia, New Zealand, US, Mauritius and La Réunion (Tassin and Riviere, 1999).
    Introduction pathways to new locations
    Agriculture: Introduced as a hedge plant to contain livestock. (Coombs et al. 1995)
    For ornamental purposes: Introduced from Western Europe as an ornamental or hedge shrub. (CDFA)


    Local dispersal methods
    Garden escape/garden waste: dumped garden waste. (Blood, Kate. pers.comm. 12 January 2001).
    Hikers' clothes/boots: Gorse seed stuck in mud clinging to human feet. (Hoshovsky, 1989)
    Natural dispersal (local): Seed dispersal is primarily by ejection from the pod (Moss 1959, in Hoshovsky, 1989).
    On animals: Parsons (1958) suggested that birds may play a part in distributing gorse seeds as "patches of the weed are often found under trees where birds have perched." Chater's (1931) observed seed collection by ants as well as by the introduced California quail in New Zealand. (Hoshovsky, 1989)
    Other (local): Hill (1949) suggests that gorse may be spread by rhizomes. (Hoshovsky, 1989)
    Translocation of machinery/equipment (local): On vehicles and graders. (Blood, Kate. pers.comm. 12 January 2001).
    Transportation of habitat material (local): Subsequent use on roadways of the gravel from seed-bearing watercourses facilitates its spread (Hill 1949). (Hoshovsky, 1989)
    Water currents: Seeds on gorse growing by watercourses are dispersed by water. (Hoshovsky, 1989)
    Management information
    Preventative measures: A Risk Assessment of Ulex europaeus for Hawai‘I and other Pacific islands was prepared by Dr. Curtis Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service. The alien plant screening system is derived from Pheloung et al. (1999) with minor modifications for use in Pacific islands (Daehler et al., 2004). The result is a score of 20 and a recommendation of: ""Likely to cause significant ecological or economic harm in Hawai‘I and on other Pacific Islands as determined by a high WRA score, which is based on published sources describing species biology and behaviour in Hawai‘I and/or other parts of the world.""

    A Risk assessment of Ulex europaeus for Australia was prepared by Pacific Island Ecosystems at Risk (PIER) using the Australian risk assessment system (Pheloung, 1995). The result is a score of 26 and a recommendation of: reject the plant for import (Australia) or species likely to be a pest (Pacific).

    Cultural: In Oregon, forest managers use fast-growing tree species to shade out gorse. This technique has also been used in New Zealand and Hawai‘i. Planting acid-tolerant, fast-growing species in gorse thickets may eventually shade out gorse without further management efforts (IPM, 2000). McCarter and Gaynor (1980; in IPM, 2000) report that the combined effect of competition of white clover (Trifolium repens) and the symbiont Rhizoctonia fungi will prevent gorse establishment in situations of extreme competition among pasture species and defoliation caused by grazing stock. It has also been stated that a healthy, well-fertilised sward of pasture which is not overgrazed or pugged will be more resistant to gorse invasion than poorly managed pasture (BOPRC, undated).

    Chemical: Many herbicides are not very effective on gorse because of the shape of the "leaves" and the thick cuticles on the spines which help prevent absorption of herbicides. Large, isolated gorse bushes can be killed by cutting and spraying the stumps with Grazon, Tordon or Escort. A motorised knapsack sprayer uses little herbicide and kills small, scattered gorse bushes. Herbicides registered for use on gorse are: activated amitrole, Answer, Escort, glyphosate, Grazon, Reglone, Tordon, Brushkiller, Touchdown, Trounce Gorsekiller and Versatill.

    Herbicide Ballistic Technology (HBT™) is a new technique designed to improve the efficiency of incipient weed management with accurate long-range delivery of effective herbicide doses. Dr. James Leary, CTAHR Invasive Weed Specialist, introduces Herbicide Ballistic Technology (HBT) to control invasive weeds in Hawaii. Trials have been carried out on banana poka (Passiflora tarminiana), Australian tree fern (Sphaeropteris cooperi), kahili ginger (Hedychium gardnerianum), including basal bark applications to strawberry guava (Psidium cattleianum).
    Please watch this YouTube video on the use of Herbicide Ballistic Technology (HBT™) in the management of gorse.

    Integrated management: Successful clearance of gorse requires a combination of methods: good pasture management, good grazing management and the appropriate follow-up herbicide application (AgResearch, 1999).

    Click here for Information about physical, chemical and biological control

    Nutrition
    Optimal growth is at soil pH of 4.5-5.0 (Meeklah 1979, in Hoshovsky, 1989). It will grow on most soil types (Meeklah 1979), from "good silt soil to plain boulders" (Birdling 1952, in Hoshovsky, 1989). It has been recorded as growing well on serpentine soils (Coombe and Frost 1956) and, though rarely, on highly calcareous soils (Chater 1931) in England. In New Zealand, gorse readily invades low fertility pastureland where the organic content of the soil is less than 4% (Matthews 1982, in Hoshovsky, 1989). It grows best where abundant soil moisture is available (Dancer et al. 1977) and does better on shady slopes than on sunny slopes (Birdling 1952, in Hoshovsky, 1989). According to Boyd (1984), gorse thrives where the water table is very high, although Zabkiewicz (1976) asserts that it does best where there is good drainage (Hoshovsky, 1989). Gorse has nitrogen-fixing bacteria located in nodules on its roots which thrive under aerobic conditions (Zabkiewicz 1976, in Hoshovsky, 1989). If the roots are flooded, bacterial metabolism slows down (Zabkiewicz 1976, in Hoshovsky, 1989).
    Reproduction
    Gorse sets flower buds in mid to late summer. If conditions are warm enough, a high proportion of these buds mature to produce pods in late autumn. In cooler climates, few flowers are produced in autumn or winter, and most buds flower synchronously in spring (Hill et al., 1991). Most seeds fall beneath the bush, and only a small proportion fall beyond 4m (Hill et al., 1996). Seeds have a hard, water-impermeable seed coat that prevents immediate germination (MacCarter and Gaynor 1980. In Hoshovsky, 1989) in all but a small proportion (R. Hill, pers. comm.). The seeds produced are small, averaging 150,000 seeds/kg (Rudolf 1974. In Hoshovsky, 1989) and are produced at the rate of 500-600 seeds/square metre, with counts of up to 20,000 seeds/square metre (Zabkiewicz and Gaskin 1978a, Hartley et al. 1980) in the top 2.5cm of soil, (Hoshovsky, 1989).
    Lifecycle stages
    Seed viability varies from place to place. In one study, they remained dormant but viable in the soil for up to 30 years, with one report of 70 years of dormancy (Zabkiewicz 1976. In Hoshovsky, 1989). In New Zealand, experiments suggested that 90% of seed would be lost after 20 years in two sites, but after 200 years in a third (Hill et al., 1996)
    This species has been nominated as among 100 of the "World's Worst" invaders
    Reviewed by: Dr Richard Hill, Richard Hill Associates. Christchurch. New Zealand.
    Compiled by: IUCN SSC Invasive Species Specialist Group
    Updates with support from the Overseas Territories Environmental Programme (OTEP) project XOT603, a joint project with the Cayman Islands Government - Department of Environment
    Last Modified: Monday, 4 October 2010


ISSG Landcare Research NBII IUCN University of Auckland