Ulex europaeus L., Fabaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results: 

Reject, score: 26 (Go to the risk assessment (Australia))
High risk, score: 20 (Go to the risk assessment (Pacific))

Common name(s): [more details]

English: common gorse, furze, gorse, whin

French: ajonc, ajonc épineux, ajonc d'Europe, bois jonc, genêt, jonc marin, vigneau

Spanish: aliaga tojo, corena, espinillo, espino amarillo, marticorena, pica pica, retama espinosa, tojo, toxo, yaguil

Habit:  shrub

Description:  "A densely branched biennial or perennial shrub with spiny habit, 1 to 6 m tall; stems woody when mature, longitudinally ridged, hairy, with numerous long spines that are modified primary branches, extended branches may have primary, secondary and tertiary spines, stem color changing green to brown when mature, prostrate stems rooting; root system fibrous in upper layers of soil but may also form a taproot; leaves alternate, about 2.5 cm long, reduced to dorsally flattened spines; flowers pea-like, yellow and showy, fragrant, mostly in leaf axils and terminal clusters; sepals deeply 2-lipped, yellow, densely hairy, 0.75 to 1.25 cm long, with ovate standard, wings and keel of equal length; filaments of 10 united stamens; pods hairy, 1 to 2 cm long, containing 2 to 6 seeds; seeds 2 to 3 mm long, rounded at one end, broader and shallowly notched at the other, with conspicuous straw-colored appendage over the scar, smooth, shiny, olive-green to brownish.  The species can be recognized by its thorny, impenetrable habit, yellow flowers, and the conspicuous appendage over the seed scar"  (Holm et al., 1997; p. 882).

"Many-branched shrubs to 6-20 dm tall; young branches usually terminating in a spine, younger parts somewhat gaucous and gray to reddish brown hirsute to tomentose. Phyllodes 4-14 mm long, usually spine-tipped. Calyx yellow, 12-16 (-20) mm long, densely villous, persistent; corolla yellow, 15-20 mm long. Pods 11-20 mm long, 6-8 mm wide, slightly compressed, densely villous. Seeds 1-4, brownish green, reniform" (Wagner et al., 1999; pp. 715-716, 1879).

Habitat/ecology:  "Gorse is a dense, spiny, woody, nitrogen-fixing legume plant that can successfully compete with pasture because of its growth habit and its prolific production of seeds, some of which are very hard and may persist in the soil for 30 to 50 years.  With little forethought, it was carried by man to all continents for use as an ornamental and a living fence or hedge plant.  In all cases it escaped to form impenetrable thickets, to invade pastures, forests, and rangelands, and to shelter unwanted animals.  Ulex frequents areas disturbed by man and prefers to move into highly productive land.  It does fix its own atmospheric N and can therefore colonize areas where little else will grow, such as heterogeneous soil and rock mixtures on mine dumps.  Gorse is frequently said to be a lime-hating palnt and to prefer a soil pH of 4 to 5; in some places this appears to be essential.  The level is also agreeable to the nitrogen-fixing bacteria of the nodules.  The weed is not confined to any special soil type and so may be seen on light sandy or heavy clay areas.  Thus, it is found on river banks, in grasslands and open forests, and as hedges or mixed with roadside scrub"  (Holm et al., 1997; p. 880).

In Hawai‘i, naturalized in open areas and along roadsides in mesic habitats from 200-2,100 m, forming dense, monotypic thickets.  "Forms dense, tall stands that shade out plants beneath.  Renders high pastures totally unproductive and impassible.  Even when killed by herbicides, the dead plants hinder access to pastures for over a year.  Gorse is an extreme fire hazard"  (Motooka et al., 2003).  In the Blue Mountains of Australia, "spreads rapidly, follows watercourses, infests swamps, forming impenetrable thickets which replace rare native plants and threaten fragile bushland environments"  (Weeds of Blue Mountains bushland).  "In Chile this species grows in the following environmental conditions:  Low altitude, interior valleys; coastal mountains, 500-2000 m; coastal areas, 0-500 m.  Humid areas, with almost constant rainfall, short dry periods are possible (generally not longer than 1 month).  Fully exposed to the sun, level areas or slopes facing north"  (Chileflora).

Propagation:  Seed. "There are reports of ejection of seeds to 5 m as the pods open, but the seeds are heavy and normally fall near the plants.  They are washed from hillsides into flowing ditches and streams and thus are moved long distances.  They are spread by animals and by man with his transport vehicles and field machines.  The reports of dispersal by birds are controversial, perhaps because there are many different carriers and because investigators do not study the same winged species.  Gorse is commonly seen under trees and around fence posts, a tell-tale sign of seed deposit by birds" (Holm et al., 1997; p. 880).

Native range:  Western Europe.

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 715-716)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 715-716)
State of Hawaii Hawaiian Islands	Moloka‘i Island	introduced invasive	Conant, Patrick (1996) (p. 1) Voucher cited: Guy Nagai s.n. (BISH)
Papua New Guinea Papua New Guinea (eastern New Guinea Island)	Papua New Guinea (eastern New Guinea Island)	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 880)

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia Australia (continental)	New South Wales	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 880)
Australia Australia (continental)	Northern Territory	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 880)
Australia Australia (continental)	Queensland	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 880) Naturalized
Central America Central America (Pacific rim)	Costa Rica (Republic of)	introduced	ILDIS Co-ordinating Centre (2013)
Central America Central America (Pacific rim)	Panama (Republic of)	introduced	ILDIS Co-ordinating Centre (2013)
China China	China (People's Republic of)	introduced	ILDIS Co-ordinating Centre (2013)
Indonesia Indonesia	Indonesia (Republic of)	introduced	ILDIS Co-ordinating Centre (2013)
Japan Japan	Japan	introduced invasive	Cronk, Q. C. B./Fuller, J. L. (2001) (p. 199)
Japan Japan	Japan	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 185)
Mexico Mexico	Mexico (United Mexican States)	introduced	Weber, Ewald (2003) (p. 444)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Owen, S. J. (1997)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 695) "Grassland, scrubland, forest margins, coastal habitats, waste places".
South America (Pacific rim) South America (Pacific rim)	Chile (Republic of)	introduced invasive cultivated	Belov, Michail (2013)
South America (Pacific rim) South America (Pacific rim)	Colombia	introduced	ILDIS Co-ordinating Centre (2013)
South America (Pacific rim) South America (Pacific rim)	Ecuador (Republic of) (continental)	introduced	ILDIS Co-ordinating Centre (2013)

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive	Lavergne, Christophe (2006) "Très envahissant"
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive	Kueffer, C./Lavergne, C. (2004) (p. 4)
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive	Baret, Stephane/Rouget, Mathieu/Richardson, David M./Lavergne, Christophe/Egoh, Benis/Dupont, Joel/Strasberg, Dominique (2006) (p. 758)
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Mauritius Island	introduced	ILDIS Co-ordinating Centre (2013)

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Canada Canada	Canada	introduced	ILDIS Co-ordinating Centre (2013)
United States (continental except west coast) United States (other states)	United States (other states)	introduced	ILDIS Co-ordinating Centre (2013)

Comments:  A "weed of national significance" in Australia.

Control:  Additional control information from the Bugwood Wiki.

Physical:  "Burning removes the shrub but stimulates seed germination.  Grazing is often used to control seedlings and regrowth" (Weber, 2003; p. 444).  "Does tolerate shade and can be suppressed by taller forest species (USFS and DOFAW).  A combined suite on controls including burning or mechanical treatment to remove biomass, followed by herbicide treatments and/or grazing to reduce seedling establishment and growth and heavy shading from planted trees may provide long-term suppression.  Quarantine, monitoring, and rapid response are necessary to prevent spread to uninfested areas"  (Motooka et al., 2003).

Chemical:  "Chemical control includes spraying seedlings with picloram or triclopyr.  Mature plants are cut and the cut stumps treated with glyphosate.  Regrowth and whole plants can be sprayed with dicamba, triclopyr, or 2,4-D plus triclopyr"  (Weber, 2003; p. 444).  "Sensitive to picloram and triclopyr, especially the amine formulation, but a good surfactant is important.  Metsulfuron with a good surfactant was also very effective on young gorse plants.  Sensitive to drizzle applications of 1 lb/acre of triclopyr ester in 1:1 crop oil:water carrier.  Dicamba, 2,4-D and tebuthiuron were not effective"  (Motooka et al., 2003).

"1. Stump swab: glyphosate (250ml/L) or metsulfuron-methyl 600g/kg (2g/L) or triclopyr 600 EC (250ml/L) or Tordon Brushkiller (100ml/L) or Vigilant gel.
2. Spray (spring-summer): triclopyr 600 EC (20ml/10L) or triclopyr 300 EC (40ml/10L).  
3. Spray (autumn-winter): metsulfuron-methyl 600g/kg (5g/10L+ penetrant (knapsack) or 20g/100L + penetrant (spraygun) or Tordon Brushkiller (250ml/100L (spraygun).
4. Frilling: With a sharp chisel or axe, make a deep cut into the sapwood at regular intervals around the base of the tree, taking care not to ring-bark the plant.  Immediately saturate each cut with undiluted Tordon Brushkiller.
5. Injection method: As each hole is drilled saturate it with undiluted Tordon Brushkiller using a sheep drench pack with a spraygun"  (Weedbusters New Zealand).

Biological: The following agents have been released in Hawai‘i:

 

Agonopterix ulicitella       (Lepidoptera: Oecophoridae)	defoliator	Portugal	established, released 1988
Apion ulicis (Coleoptera: Apionidae)	seed feeder	England	established, released 1955
Apion scutellare (Coleoptera: Apionidae)	stem gall former	England	not established, released 1989, 1990, 1991
Pempilia genistella (Lepidoptera: Pyralidae)	stem borer	Portugal	not established, released 1996, 1998
Sericothrips staphylinus       (Thysanoptera: Thripidae)	defoliator	England	established, released 1990
Tetranychus lintearius       (Acarina: Tetranychidae)	defoliator	England	established, released 1995

"Several biological control agents have been released in Hawai‘i including the gorse spider mite (Tetranychus lintearius).  Though damage is noticeable on individual gorse plants, the agents do not seem to be reducing gorse populations"  (Motooka et al., 2003).  "Biological control of gorse (Ulex europaus) was attempted in Hawaii as early as 1925, but the agents failed to establish. In the 1950s, several weevils of the genus Apion were released to control gorse. Of these, only the seed weevil Apion ulicis, released in 1955, became established. Apion scutellare, a stem-gall former was released over three years from 1989 but did not become established. Other insect agents released between 1988 and 1998 include the defoliators Agonopterix ulicitella, Sericothrips staphylinus, Tetranychus lintearius, and a stem borer (Pempelia genistella). A rust fungus Uromyces pisi f. sp. europaei was introduced in 2000. Several of the biological control agents became established in Hawaii and appear to cause damage to gorse, but their overall impacts on gorse populations are not apparent" (Biological control in Hawai‘i).  See Smith et al., 2002, pp. 53-61, for additional information on biological control efforts in Hawai‘i.