Cytisus scoparius - (L.) Link
Scotch Broom
Other Common Names: Scotch broom
Taxonomic Status: Accepted
Related ITIS Name(s): Cytisus scoparius (L.) Link (TSN 501966)
Unique Identifier: ELEMENT_GLOBAL.2.138657
Element Code: PDFAB18060
Informal Taxonomy: Plants, Vascular - Flowering Plants - Pea Family
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Fabales Fabaceae Cytisus
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Concept Reference
Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Cytisus scoparius
Conservation Status

NatureServe Status

Global Status: GNR
Global Status Last Changed: 22Mar1994
Rounded Global Status: GNR - Not Yet Ranked
Nation: United States
National Status: NNA
Nation: Canada
National Status: NNA (01Aug2016)

U.S. & Canada State/Province Status
United States Alabama (SNA), California (SNA), Connecticut (SNA), Delaware (SNA), District of Columbia (SNA), Georgia (SNR), Hawaii (SNA), Idaho (SNA), Maine (SNA), Maryland (SNA), Massachusetts (SNR), Michigan (SNA), Montana (SNA), New Jersey (SNA), New York (SNA), North Carolina (SNA), Ohio (SNA), Oregon (SNA), Pennsylvania (SNA), Rhode Island (SNA), South Carolina (SNA), Tennessee (SNA), Utah (SNA), Virginia (SNA), Washington (SNA), West Virginia (SNA)
Canada British Columbia (SNA), Nova Scotia (SNA), Prince Edward Island (SNA)

Other Statuses

NatureServe Global Conservation Status Factors

Other NatureServe Conservation Status Information

U.S. States and Canadian Provinces
Color legend for Distribution Map
NOTE: The distribution shown may be incomplete, particularly for some rapidly spreading exotic species.

U.S. & Canada State/Province Distribution
United States ALexotic, CAexotic, CTexotic, DCexotic, DEexotic, GA, HIexotic, IDexotic, MA, MDexotic, MEexotic, MIexotic, MTexotic, NCexotic, NJexotic, NYexotic, OHexotic, ORexotic, PAexotic, RIexotic, SCexotic, TNexotic, UTexotic, VAexotic, WAexotic, WVexotic
Canada BCexotic, NSexotic, PEexotic

Range Map
No map available.

Ecology & Life History Not yet assessed
Economic Attributes Not yet assessed
Management Summary Not yet assessed
Population/Occurrence Delineation Not yet assessed
Population/Occurrence Viability
U.S. Invasive Species Impact Rank (I-Rank)
Disclaimer: While I-Rank information is available over NatureServe Explorer, NatureServe is not actively developing or maintaining these data. Species with I-RANKs do not represent a random sample of species exotic in the United States; available assessments may be biased toward those species with higher-than-average impact.

I-Rank: High
Rounded I-Rank: High
I-Rank Reasons Summary: Scotch Broom is considered an aggressive invader and has invested more than 2 million acres in Washington, Oregon and California. It has also escaped from cultivation in the east, however, it is not as problematic there. This species, when it has established, alters abiotic characters of the ecosystem including adding nitrogen to the soil and altering the fire regime. It invades grasslands, shrublands, open forests and pastures. Finally, it produces copious seeds and requires active management.
Subrank I - Ecological Impact: High
Subrank II - Current Distribution/Abundance: High/Medium
Subrank III - Trend in Distribution/Abundance: Medium
Subrank IV - Management Difficulty: High/Low
I-Rank Review Date: 25Sep2007
Evaluator: Oliver, L., minor rev. K. Gravuer
Native anywhere in the U.S?
Native Range: Scotch broom is native to the Bristish Isles and southern Europe (Hoshovsky 2004). Randall and Marinelli (1996) also report that this species is native to North Africa.

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Screening Questions

S-1. Established outside cultivation as a non-native? YES
Comments: Scotch broom is established as a non-native throughout much of the eastern United States, from Maine to Georgia and Alabama. It has not escaped in the midwest, but has escaped and is problematic in west. In the western United States, it has escaped from cultivation from Washington south to California. It is absent from Nevada, but present in other non-coastal western states including Idaho, Montana and Utah (Kartesz 1999, Hoshovsky 2004).

S-2. Present in conservation areas or other native species habitat? Yes
Comments: It is reported that in California this species has invaded grassland areas of open hills and lower chaparrell in Marin County (Hoshovsky 2004). It also colonizes shrublands and open canopy forests (Randall and Marinelli 1996). Commonly invades intact prairie (grassland) remnants in Western Washington (S. Erickson pers. comm. 2006).

Subrank I - Ecological Impact: High

1. Impact on Ecosystem Processes and System-wide Parameters:High significance
Comments: Scotch broom alters the abiotic factors of the ecosystems where it occurs by increasing the fuel load. This species is flamable and carries fire to the canopy where the fire burns hotter and causes more destruction (Randall and Marinelli 1996). Also, this species thrives in soils that other plants can't tolerate. It is capable of growing vigorously in nitrogen poor soils because it contains nitrogen fixing bacteria in its root nodules (Randall and Marinelli 1996). So, this shrub species changes the abiotic factors by acting as a conduit for the fire from the ground to the canopy (where fire has historically been restricted) and by increasing the nitrogen levels in poor quality soils.

2. Impact on Ecological Community Structure:Moderate significance
Comments: This species alters at least one layer of the vegetation. It is a shrub that invades grasslands and open forests and alters the herbaceous layer by shading it. It may alter the canopy layer indirectly since it allows fire to reach this upper layer of vegetation (Randall and Marinelli 1996).

3. Impact on Ecological Community Composition:High significance
Comments: Scotch broom is reported to form monocultures and become so dense that the areas where it occurs are impenetrable (Hoshovsky 2004). In addition, this species excludes the native vegetation to such an extent that common animals such as deer and quail are unable to forage (Hoshovsky 2004).

4. Impact on Individual Native Plant or Animal Species:Insignificant
Comments: No information was found reporting that this species has a disproportionate negative impact on particular native species.

5. Conservation Significance of the Communities and Native Species Threatened:Moderate significance
Comments: Commonly invades intact prairie (grassland) remnants in Western Washington (S. Erickson pers. comm. 2006).

Subrank II. Current Distribution and Abundance: High/Medium

6. Current Range Size in Nation:High/Moderate significance
Comments: Scotch broom has escaped from cultivation throughout the eastern United States, from Maine south to Georgia. It is absent from the midwest, but present in the west. It occurs from Washington south to California, and is in other states that are not coastal including Idaho, Montana and Utah (Kartesz 1999).

7. Proportion of Current Range Where the Species is Negatively Impacting Biodiversity:Moderate significance
Comments: This species appears to have a negative impact in most of the places where it invades, however, the effects are far worse in the west than they are in the eastern United States. Randall and Marinelli (1996) say that more than 2 million acres in Washington, Oregon and the coastal Sierra Nevada foothill regions of California are now colonized by this species.

8. Proportion of Nation's Biogeographic Units Invaded:Medium/Low significance
Comments: This species occurs at the very least in several ecoregions, however, the exact number is not known. Since it covers 2 millions acres in the west (Randall and Marinelli 1996) it definitely spans more than 5 ecoregions (TNC 2001).

9. Diversity of Habitats or Ecological Systems Invaded in Nation:Moderate significance
Comments: The natural habitats Scotch broom invades include grasslands, shrublands and canopy forests (Randall and Marinelli 1996). Commonly invades intact prairie (grassland) remnants in Western Washington (S. Erickson pers. comm. 2006). In addition, it also is reported to invade pastures and wastelands (Whitson et al. 1996).

Subrank III. Trend in Distribution and Abundance: Medium

10. Current Trend in Total Range within Nation:Moderate significance
Comments: Scotch broom is spreading in the west. It is described as 'aggressive' and 'spreads rapidly' (Hoshovsky 2004) and has already invaded more than 2 million acres in Washington, Oregon and California (Randall and Marinelli 1996). It is also reported to be infesting large areas in British Columbia and a few small areas along the Atlantic Coast of the United States (Randall and Marinelli 1996).

11. Proportion of Potential Range Currently Occupied:Low significance
Comments: This species has invaded shrublands and grasslands (Randall and Marinelli 1996) and is not documented from the midwestern United States. Since the midwest is made up of prairies and other open habitats it does seem plausible that this species could invade midwestern states.

12. Long-distance Dispersal Potential within Nation:High significance
Comments: In some parts of its non-native range, and especially in California, this species is known to disperse long distances frequently. Long distance dispersal takes place when this species grows along roadsides and vehicles transport the seeds, and when the species grows near rivers and water transports the seeds. In addition, birds and other animals have been reported to transport the seeds to isolated areas (Hoshovsky 2004).

13. Local Range Expansion or Change in Abundance:Moderate significance
Comments: Scotch broom has spread significantly in the recent past, and mostly in the western United States. In California, it has been categorized as a Class C noxious weed species and a non-scientific census reports that it (and other broom species) are spreading (Hoshovsky 2004).

14. Inherent Ability to Invade Conservation Areas and Other Native Species Habitats:Moderate significance
Comments: This species usually invades open areas, but does invade some intact natural habitats such as grasslands, shrublands and open forests (Randall and Marinelli 1996, S. Erickson pers. comm. 2006).

15. Similar Habitats Invaded Elsewhere:Medium/Low significance

16. Reproductive Characteristics:High significance
Comments: Cytisus scoparius has a number of reproductive characters that allow it to rapidly colonize a suitable area. Scotch broom is capable of reproducing by seed or vegetatively, it sprouts after cutting, produces numerous seeds (60 seed pods per bush each with 5-8 seeds), its seeds have a hard seed coat which can survive water transport, and grows rapidly in the first 4-5 years. Finally, the seeds have been reported to be viable for up to 80 years (Hoshovsky 2004).

Subrank IV. General Management Difficulty: High/Low

17. General Management Difficulty:Moderate significance
Comments: Scotch broom is known for forming monocultures which are difficult to eradicate. There are many methods used to remove this species and they span from integrated pest management, to physical, manual, and other mechanical methods (Hoshovsky 2004).

18. Minimum Time Commitment:High/Low significance
Comments: Information was found on all of the methods used to remove Scotch broom, but no information was found about how long it takes to remove the species. It is reasonable that this species takes at least 2 years, and probably more, to eradicate it given the involved methods used to remove it.

19. Impacts of Management on Native Species:Medium/Low significance
Comments: Since this species is managed for, and many methods are used, it is assumed that there are some negative impacts to native species when these methods are employed.

20. Accessibility of Invaded Areas:Unknown

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

  • Hoshovsky, M. ed. 2004. Element Stewardship Abstract for Cystisus scoparius and Genista monspessulanus. The Nature Conservancy.

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Kartesz, J.T. 1996. Species distribution data at state and province level for vascular plant taxa of the United States, Canada, and Greenland (accepted records), from unpublished data files at the North Carolina Botanical Garden, December, 1996.

  • Kartesz, J.T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. First edition. In: Kartesz, J.T., and C.A. Meacham. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, N.C.

  • Randall, J.M. and J. Marinelli (eds.) 1996. Invasive plants: weeds of the global garden. Brooklyn Botanic Garden, New York.

  • The Nature Conservancy. 2001. Map: TNC Ecoregions of the United States. Modification of Bailey Ecoregions. Online . Accessed May 2003.

  • Whitson, T.D. (ed.), L.C. Burrill, S.A. Dewey, D.W. Cudney, B.E. Nelson, R.D. Lee, R. Parker. 1996. Weeds of the West. 5th edition. The Western Society of Weed Science in cooperation with the Western United States Land Grant Universities Cooperative Extension Services, Newark, CA. 630 pp.

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