Research directed by C. Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service

Information on Risk Assessments
Original risk assessment

Ulex europaeus (gorse)

Answer

1.01

Is the species highly domesticated?

y=-3, n=0

n

1.02

Has the species become naturalized where grown?

y=-1, n=-1

y

1.03

Does the species have weedy races?

y=-1, n=-1

n

2.01

Species suited to tropical or subtropical climate(s) (0-low; 1-intermediate; 2-high) – If island is primarily wet habitat, then substitute “wet tropical” for “tropical or subtropical”

See Append 2

1

2.02

Quality of climate match data (0-low; 1-intermediate; 2-high) see appendix 2

2

2.03

Broad climate suitability (environmental versatility)

y=1, n=0

y

2.04

Native or naturalized in regions with tropical or subtropical climates

y=1, n=0

y

2.05

Does the species have a history of repeated introductions outside its natural range? y=-2

?=-1, n=0

y

3.01

Naturalized beyond native range y = 1*multiplier (see Append 2), n= question 2.05

y

3.02

Garden/amenity/disturbance weed y = 1*multiplier (see Append 2)

n=0

y

3.03

Agricultural/forestry/horticultural weed y = 2*multiplier (see Append 2)

n=0

y

3.04

Environmental weed y = 2*multiplier (see Append 2)

n=0

n

3.05

Congeneric weed y = 1*multiplier (see Append 2)

n=0

y

4.01

Produces spines, thorns or burrs

y=1, n=0

y

4.02

Allelopathic

y=1, n=0

n

4.03

Parasitic

y=1, n=0

n

4.04

Unpalatable to grazing animals

y=1, n=-1

n

4.05

Toxic to animals

y=1, n=0

n

4.06

Host for recognized pests and pathogens

y=1, n=0

n

4.07

Causes allergies or is otherwise toxic to humans

y=1, n=0

y

4.08

Creates a fire hazard in natural ecosystems

y=1, n=0

y

4.09

Is a shade tolerant plant at some stage of its life cycle

y=1, n=0

n

4.1

Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island)

y=1, n=0

n

4.11

Climbing or smothering growth habit

y=1, n=0

n

4.12

Forms dense thickets

y=1, n=0

y

5.01

Aquatic

y=5, n=0

n

5.02

Grass

y=1, n=0

n

5.03

Nitrogen fixing woody plant

y=1, n=0

y

5.04

Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers)

y=1, n=0

n

6.01

Evidence of substantial reproductive failure in native habitat

y=1, n=0

n

6.02

Produces viable seed.

y=1, n=-1

y

6.03

Hybridizes naturally

y=1, n=-1

y

6.04

Self-compatible or apomictic

y=1, n=-1

6.05

Requires specialist pollinators

y=-1, n=0

n

6.06

Reproduction by vegetative fragmentation

y=1, n=-1

y

6.07

Minimum generative time (years) 1 year = 1, 2 or 3 years = 0, 4+ years = -1

See left

2

7.01

Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas)

y=1, n=-1

y

7.02

Propagules dispersed intentionally by people

y=1, n=-1

y

7.03

Propagules likely to disperse as a produce contaminant

y=1, n=-1

n

7.04

Propagules adapted to wind dispersal

y=1, n=-1

n

7.05

Propagules water dispersed

y=1, n=-1

y

7.06

Propagules bird dispersed

y=1, n=-1

7.07

Propagules dispersed by other animals (externally)

y=1, n=-1

y

7.08

Propagules survive passage through the gut

y=1, n=-1

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

y

8.02

Evidence that a persistent propagule bank is formed (>1 yr)

y=1, n=-1

y

8.03

Well controlled by herbicides

y=-1, n=1

n

8.04

Tolerates, or benefits from, mutilation, cultivation, or fire

y=1, n=-1

y

8.05

Effective natural enemies present locally (e.g. introduced biocontrol agents)

y=-1, n=1

Total score:

20

Notes

Source

1.01

No evidence

1.02

Introduced to many montane regions of the tropics, including Peru, La Réunion, Sri Lanka, St Helena and Hawai'i. U. europaeus is now naturalized in Sri Lanka and is considered a serious pest on two Hawaiian Islands.

http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm

1.03

No evidence

2.01

Native to Europe.

(1)http://www.ildis.org/LegumeWeb/6.00/taxa/5775.shtml (2)http://www.wes.army.mil/el/pmis/plants/html/ulex_eur.html

2.02

Introduced to many montane regions of the tropics, including Peru, La Réunion, Sri Lanka, St Helena and Hawai'i. U. europaeus is now naturalized in Sri Lanka and is considered a serious pest on two Hawaiian Islands. … The species was introduced to many temperate regions and is a serious pests. In La Réunion it has extensively invaded heathlands, particularly in areas disturbed by cultivation and grazing. It forms monotypic stands in South America including in areas previously forested. Invasive in many temperate areas were the plant was often used as hedge material.

http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm

2.03

(1)Temperate oceanic climate with mild winters and mild to cool summers. Absent from arable and wetland habitats. (2)It grows as low as 460 m a.s.l. but most of its distribution is between 630 and 2220 m. In South America the shrub is found up to 3200 m.It grows as low as 460 m a.s.l. but most of its distribution is between 630 and 2220 m. (3)It cannot survive in arid climates, or in continental regions where there are extremes of heat and cold.

(1)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm (2)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm (3)http://tncweeds.ucdavis.edu/esadocs/documnts/ulexeur.html

2.04

Introduced to many montane regions of the tropics, including Peru, La Réunion, Sri Lanka, St Helena and Hawai'i. U. europaeus is now naturalized in Sri Lanka and is considered a serious pest on two Hawaiian Islands. … The species was introduced to many temperate regions and is a serious pests. In La Réunion it has extensively invaded heathlands, particularly in areas disturbed by cultivation and grazing. It forms monotypic stands in South America including in areas previously forested. Invasive in many temperate areas were the plant was often used as hedge material.

http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm

2.05

(1)Introduced to several countries over the world. (2)Introduced to many montane regions of the tropics, including Peru, La Réunion, Sri Lanka, St Helena and Hawai'i. U. europaeus is now naturalized in Sri Lanka and is considered a serious pest on two Hawaiian Islands.

(1)http://www.ildis.org/LegumeWeb/6.00/images/Ulex_europaeus.gif (2)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm

3.01

Introduced to many montane regions of the tropics, including Peru, La Réunion, Sri Lanka, St Helena and Hawai'i. U. europaeus is now naturalized in Sri Lanka and is considered a serious pest on two Hawaiian Islands. … The species was introduced to many temperate regions and is a serious pests. In La Réunion it has extensively invaded heathlands, particularly in areas disturbed by cultivation and grazing. It forms monotypic stands in South America including in areas previously forested. Invasive in many temperate areas were the plant was often used as hedge material.

http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm

3.02

(1)Common gorse is considered an invasive species. By crowding out native vegetation in the western United States it is causing the loss of valuable grassland habitat. [human-disburbed environments] (2) In La Réunion it has extensively invaded heathlands, particularly in areas disturbed by cultivation and grazing. It forms monotypic stands in South America including in areas previously forested.[human-disturbed environments] (3)Gorse invades infertile or disturbed sites, sand dunes, gravel bars, fence rows, overgrazed pastures, logged areas, and burned-over lands

(1)http://nationalatlas.gov/wdulexm.html (2)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm (3)http://tncweeds.ucdavis.edu/esadocs/documnts/ulexeur.html

3.03

(1)It is threatening agricultural and grazing lands. Thickets are impenetrable to humans and have persistent spiny litter. (2)Gorse (Ulex europaeus) is the most feared scrub weed in New Zealand grazing land. This weed has infested 657,000 ha of New Zealand's pastures and past attempts at eradication of gorse from hill country have met with limited success. (3)Prinicipal weed in Chile. (4)A weed of pastures and wastelands around Olinda, Maui, and Humuula Hawaii...forms impenetrable thickets (5)In Hawaii, temporary control was undertaken in the 1970s using 2,4-5 T. The ban of the herbicide and lack of funding ended the programme. A task force was later set up to coordinate a management approach which included the following four control programmes: a/ containment: using Tordon 22K strips along roadsides were first targeted to eliminate the possibility of seed transport to new areas, b/ long-term biological: search for control agents in Europe which in 1984 resulted in the release of a seed weevil (Apion ulicis

(1)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm (2)TI: CONTROL OF GORSE IN HILL COUNTRY AN ECONOMIC ASSESSMENT OF CHEMICAL AND BIOLOGICAL METHODS.
AU: KRAUSE-M-A {a}; BECK-A-C; DENT-J-B
SO: Agricultural-Systems. 1988; 26 (1): 35-50..
PY: 1988 (3)Holm et al. 1997. An electronic atlas of weeds and invasive specis. CD-ROM database. Version 1. (4)Hasselwood, E.L. and G.G. Motter. 1983.Handbook of Hawaiian Weeds. University of Hawai‘i Press. (5)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm (6)http://www.botany.hawaii.edu/faculty/carr/ule_eur.htm

3.04

disturbance weed

3.05

[Other two congeners U. gall and U minor are considered as weed and subjected to control]
(1) AB: Several formulae of weedkillers were sprayed, using 200-600 litres of water per ha, to eradicate gorse from grasslands in N. and NW Spain. A mixture of 960 g of picloram and 3600 g of 2,4,5-T ester, applied in late July 1967, gave the best effect, eliminating 91% of the gorse.
(2) AB: Gorse (Ulex europaeus, U. minor and, probably, hybrids) is the most widespread exotic shrub species in New Zealand and, because it occupies potentially highly productive country, its control is of considerable significance.

(1) Gonzalez Esparcia, E.; Penalva Rodriguez, F. (1978) The use of various herbicidal treatments based on picloram, 2,4,5-T and 2,4-D to combat gorse (Ulex gallii, Planch)., 1978, 26 pp.
(2) Meeklah, A. (1979) Controlling gorse (in Otago and Southland). New Zealand Journal of Agriculture, 1979, Vol.139, No.2, p.51, 53

4.01

(1)An extremely common spiny shrub … (2)Gorse is a shrub up to 2 m tall having branches that end in spiny tips. Lacking true leaves except in the juvenile stage, the petioles are reduced to linear spines.

(1)http://www.habitas.org.uk/flora/species.asp?item=3211 (2)http://www.wes.army.mil/el/pmis/plants/html/ulex_eur.html

4.02

No evidence

4.03

No evidence

http://www.omnisterra.com/bot/pp_home.cgi?name=Ule+europaeus&submit=Submit+Query&search=all

4.04

' … Recent research has shown that the grazing by goats and sheep is a possible alternative for gorse control. …'

TI: CONTROL OF GORSE IN HILL COUNTRY AN ECONOMIC ASSESSMENT OF CHEMICAL AND BIOLOGICAL METHODS.
AU: KRAUSE-M-A {a}; BECK-A-C; DENT-J-B
SO: Agricultural-Systems. 1988; 26 (1): 35-50..
PY: 1988

4.05

' … Recent research has shown that the grazing by goats and sheep is a possible alternative for gorse control. …'

TI: CONTROL OF GORSE IN HILL COUNTRY AN ECONOMIC ASSESSMENT OF CHEMICAL AND BIOLOGICAL METHODS.
AU: KRAUSE-M-A {a}; BECK-A-C; DENT-J-B
SO: Agricultural-Systems. 1988; 26 (1): 35-50..
PY: 1988

4.06

(1)Pests and diseases: A large number of insects have found feeding on the shrub, but at very low densities. (2) This site list 43 fungi species to be associated with Ulex europaeus.  *Uromyces pisi-sativi: United Kingdom - 36425
(3) AB: The results of field trials with contact fungicides to compare their efficacy with that of systemic sterol biosynthesis inhibiting fungicides against rust (Uromyces pisi ) and powdery mildew (Erysiphe pisi ) of peas carried in Hungary in 1993 and 1994 are summarized.
[Uromyces pisi-sativum is considered a rare pea disease; http://www.which.net/gardeningwhich/advice/rustvegetables.html]

(1)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm (2)http://nt.ars-grin.gov/fungaldatabases/all/FindRecOneFungusFrame.cfm
(3) Füzi, I. (1995) Fungicides against diseases of pea, Pisum sativum L., in Hungary. Pesticide Science, 1995, Vol.45, No.3, pp.292-295

4.07

Poisonous parts: The branches and the fruits are strongly poisonous. Effect: The contents materials affect at first exciting the central nervous system, later however laehmend. To a time between ¼ up to one hour it comes to burning in the mouth and throat area, nausea, strong thirst and central caused vomiting. In the vomit bloody portions can be present. To stomach intestine cramps come sweating, headache, excitation conditions, Delirien and mydriasis. Muscle twitching and cramps are further signs. With lethal intoxications a general paralysis is recognizable. Death occurs in the cycle collapse by a paralysis of the respiration.

http://translate.google.com/translate?hl=en&sl=de&u=http://www.gifte.de/
ulex_europaeus.htm&prev=/search%3Fq%3DUlex%2Beuropaeus%26start%3D10
%26hl%3Den%26lr%3D%26ie%3DUTF-8%26sa%3DN

4.08

In La Réunion it is said that U. europaeus has a higher combustible biomass and is probably more flammable than the native vegetation. … U. europaeus represents a fire hazard to private property.

http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm

4.09

(1)The shrub is light demanding and dies through shading but seedlings may become established under its own canopy (2)Prefers dry sunny positions (3)Sunny position (4)full sun (5)Zabkiewicz (1976) states that adult gorse plants have a relatively low light requirement, and the shading effect of other species has little effect on gorse flowering and seeding. In contrast, Amme (1983) mentions that gorse is relatively intolerant to heavy shade, producing sparse foliage and few flowers. Hackwell (1980) agrees, describing gorse as a "pioneer plant" which grows best in unshaded sites and calling it a "light demanding plant."

(1)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm (2)http://www.hedging.uk.com/list_hedge.htm (3)http://www.bucknur.com/acatalog/Index_Hedging__Trees__Shrubs___Conifers_E_H_5.html (4)http://plants.gardenbed.com/70/6935_lan.asp (5)http://tncweeds.ucdavis.edu/esadocs/documnts/ulexeur.html

4.1

(1)Tolerates most soil types, including serpentine, but seldom grows in high calcium (calcareous) soils. (2)dry acid soils

(1)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm (2)http://www.bucknur.com/acatalog/Index_Hedging__Trees__Shrubs___Conifers_E_H_5.html

4.11

Non climbing shrub.

http://www.ildis.org/LegumeWeb/6.00/taxa/5775.shtml

4.12

(1)Gorse is a rigid spiny perennial that can form dense impenetrable thickets. (2)In the tropics it forms monotypic stands in mountainous areas subjected to large herbivore disturbance and/or fire. (3)U. europaeus forms impenetrable and often extensive thickets with as many as 60,000 stems/ha.

(1)http://www.wes.army.mil/el/pmis/plants/html/ulex_eur.html (2)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm (3)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm

5.01

Terrestrial

5.02

Much-branched evergreen shrub to 2-4 m tall.

http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm

5.03

The species forms nitrogen-fixing root nodules. … Its nitrogen fixing capacity allow growth under conditions of extreme infertility.

http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm

5.04

Much-branched evergreen shrub to 2-4 m tall.

http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm

6.01

No evidence

6.02

Seeds can germinate after been subjected to temperature up to 88°C. … Seed germination and seedling survival is lower under a U. europaeus canopy than in the open.

http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm

6.03

In SW Britain U. europaeus hybridizes with U. galli Planch. where their flowering periods may overlap. It exhibits much intra- and inter- population variation in morphology. Leaves are present only at the seedling stage but thereafter are replaced by spines or scales.

http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm

6.04

Insect exclusion reduces seed production to zero [but still might self if bees pollinate it]

Herrera, J.1999. Fecundity above the species level: ovule number and brood size in the Genisteae (Fabaceae: Papilionoideae). International Journal of Plant Sciences, 160:887-896

6.05

The hermaphrodite yellow flowers are usually insect-pollinated and 1 to 3 of them are bone on axillary clusters.

http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm

6.06

Hill (1949) suggests that gorse may be spread by rhizomes. (2)The plant reproduces by both creeping roots or by seeds.

(1)http://www.conserveonline.org/2001/05/d/en/ulexeur.PDF (2)http://tncweeds.ucdavis.edu/esadocs/documnts/ulexeur.html

6.07

Gorse grows very quickly. 6000 kg/ha of dry matter can be produced in one-year-old stands [minimum estimate for a fast growing medium sized shrub]

http://tncweeds.ucdavis.edu/esadocs/documnts/ulexeur.html

7.01

(1) "Other possible means of seed dispersal include mud which contains gorse seed clinging to livestock or human feet. " (2)soil movement

(1) http://www.conserveonline.org/2001/05/d/en/ulexeur.PDF (2)http://pi.cdfa.ca.gov/weedinfo/ULEX2.html

7.02

(1) 'On marginal land it is a source of food for cattle and ponies and formerly, after removal of spines, it was used for fodder.' (2)It was originally used as an ornamental

(1)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm (2)http://tncweeds.ucdavis.edu/esadocs/documnts/ulexeur.html

7.03

Probably not - relativley large seeds - 'Seeds 2-6, shiny green to brown, smooth, +/- triangular, flattened, ~ 3 mm long, with a straw-colored appendage.'

http://pi.cdfa.ca.gov/weedinfo/ULEX2.html

7.04

(1)When the legumes mature, the pods dehisce and the seeds are ejected for some distance. (2)Pods (2 cm long) open explosively releasing 2 to 6 seeds and the seeds (6.2 mg, 3.3 x 2.3 mm) may be further dispersed by ants. (3)Most seeds are ejected to within 5 m of the parent shrub when pods snap open at maturity. Some seeds may disperse to greater distances with human activities, water, soil movement, animals, and ants.

(1)http://www.wes.army.mil/el/pmis/plants/html/ulex_eur.html (2)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm (3)http://pi.cdfa.ca.gov/weedinfo/ULEX2.html

7.05

(1) "The seed of gorse growing along streams is spread by water. Subsequent use on roadways of the gravel from these seed-bearing watercourses facilitates its spread (Hill 1949)."

(1) http://www.conserveonline.org/2001/05/d/en/ulexeur.PDF

7.06

(1) "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. Of more substance is Chater's (1931) observation of active gorse seed collection by ants as well as by the introduced California quail in New Zealand.The effect of quail on gorse seed dispersal has not been studied in California."

(1) http://www.conserveonline.org/2001/05/d/en/ulexeur.PDF

7.07

(1) "Pods (2 cm long) open explosively releasing 2 to 6 seeds and the seeds (6.2 mg, 3.3 x 2.3 mm) may be further dispersed by ants. "

(1) http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm

7.08

(1)Seeds are hard-coated. [quails or grazing animal might eat grose seeds, but only speculation]

(1)http://www.wes.army.mil/el/pmis/plants/html/ulex_eur.html (2)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm (3)http://pi.cdfa.ca.gov/weedinfo/ULEX2.html
(4) http://www.conserveonline.org/2001/05/d/en/ulexeur.PDF

8.01

(1)The bracts are persistent and subtend the fruit which is a hairy legume containing two to four seeds. (2)Pods ovoid to oblong, 1-2 cm long, slightly flattened, dark brown, covered with tawny spreading wavy hairs, partially enclosed by the calyx. Seeds 2-6, shiny green to brown, smooth, +/- triangular, flattened, ~ 3 mm long, with a straw-colored appendage.
(3) AB: "Gorse (Ulex europaeus, U. minor and, probably, hybrids) is the most widespread exotic shrub species in New Zealand and, because it occupies potentially highly productive country, its control is of considerable significance. The seed has a hard coat and may lie dormant for 30 years or more; as many as 10 000 seeds/m2 have been counted in the soil. " [soil seed bank attend 10,000 seeds/m2]
(4) "The seeds produced are very small, averaging 150,000 seeds/kg (Rudolf 1974) and are produced at the rate of 500-600 seeds/square meter, with counts of up to 20,000 seeds/square meter (Zabkiewicz and Gaskin 1978a, Hartley et al. 1980) in the top 2.5 cm of

(4) http://www.conserveonline.org/2001/05/d/en/ulexeur.PDF

8.02

(1) It produces large amounts of seed that can remain viable in the soil for 30 years or more. (2)Seeds are hard-coated and can survive for more than 30 years under field conditions. Large soil seed banks often accumulate.

(1)http://www.wes.army.mil/el/pmis/plants/html/ulex_eur.html (2)http://pi.cdfa.ca.gov/weedinfo/ULEX2.html

8.03

(1)Gorse is difficult to control because its waxy cuticle inhibits herbicide penetration. (2)Bushes start degenerating after 20 years unless fire occurs.

(1)http://www.wes.army.mil/el/pmis/plants/html/ulex_eur.html (2)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm

8.04

(1)When cut it coppices freely and following fire seed germination leads to high densities of seedlings. … Requires disturbance, such as fire or large grazing herbivores, for establishment. (2)Plants cut or burned to ground level may resprout from the crown. Burning often stimulates a flush of seedling germination after the first rain. Browsing and trampling by goats can greatly reduce seedling establishment and crown re-growth.

(1)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp18.htm (2)http://pi.cdfa.ca.gov/weedinfo/ULEX2.html

8.05

The gorse seed weevil (Apion ulicis) and spider mite (Tetranychus lintearius) are introduced biocontrol agents currently established in California. The seed weevil reduces seed production, but cannot kill established stands. Heavy mite infestations can kill branches and are apparent by the dense webbing that covers the foliage.

http://pi.cdfa.ca.gov/weedinfo/ULEX2.html