COMMON NAME

Scotch broom


FULL SCIENTIFIC NAME

Cytisus scoparius (L.) Link


FAMILY NAME COMMON

Pea family


FAMILY SCIENTIFIC NAME

Cytisus scoparius


IMAGES


Flowers

Habit

Habit/Habitat

Flowers on branch

Incursion

NOMENCLATURE/SYNONYMS

Synonyms: Sarothamnus scoparius (L.) Wimmer ex Koch


DESCRIPTION

Botanical Glossary

Cytisus scoparisis a short perennial shrub that grows up to 2 m (6.5 ft.) tall. The green branches are stiff, slender and 5-angled. The stems remain green throughout the year. The leaves are arranged alternately. The upper surface of the leaf is dark green while the lower surface is lighter and pubescent. The lower leaves of the plant are small, have petioles measuring 2-8 mm (0.07-0.3 in.) in length, and are 3-foliate. The leaflets are obovate in shape, and measure 5-10 mm (0.25-0.4 in.) in length. The upper leaves are sessile, simple and undivided. The flowers of Cytisus scoparis are usually bright yellow (though there are many cultivars that range from pale yellow to pink to red in color). They are either solitary or paired in the upper axils of the plant, forming long, terminal racemes. The flowers measure 2-2.5 cm (0.75-1 in.) in length. The bilabiate calyx is glabrous and measures 7 mm (0.25 in.) long. Blooming occurs in late May or June. The fruit are brownish pods (legumes) that ripen during the late summer. They measure 3-5 cm (1-2 in.) in length and are hairy along the margins. The seeds are small, measuring 2 mm (0.7 in.) in length. They are multicolored (green, brown, dark brown, rusty) and generally obovate to round in shape. Page References Bailey 568, Fernald 890, Gleason & Cronquist 277, Holmgren 259, Magee & Ahles 652, Newcomb 106, Peterson & McKenny 154. See reference section below for full citations.


SIMILAR SPECIES


REPRODUCTIVE/DISPERSAL MECHANISMS

Cytisus scoparius reproduces primarily via seed. Its seed capsules have a capacity for ballistic dispersal, most notably when dry. Once ejected, dispersal of the seeds can be further aided by wind. Moving water is also a possible method of seed dispersal. Some vegetative reproduction can occur in the form of resprouting.


DISTRIBUTION

Cytisus scoparius is native to the British Isles and central and southern Europe. It is found in British Columbia and the western U.S. It is also found from Maine to Michigan and south from Alabama to Georgia. It is occurs in all of the New England states with the exception of Vermont, primarily in coastal regions. It is currently most problematic in the western U.S. and British Columbia; it has spread to occupy more than 2 million acres in CA, WA and OR (Bossard, 1996).


HISTORY OF INTRODUCTION IN NEW ENGLAND

Cytisus scoparius was planted on the islands of Nantucket and Martha's Vinyard in the late 1800's for a combination of its appearance and its dune stabilizing capabilities. It was planted near Provincetown, MA in 1875 for much the same reasons. An 1895 record from Woods Hole Massachusetts noted that it had "firmly established" in a field behind a local workshop (Rhodora, Vol. 2: 89). Robinson (1908) reported that Cytisus scoparius was found in "sandy barrens, etc." from southeast Massachusetts to Virginia and southwest.


HABITATS IN NEW ENGLAND

,Coastal Beach or Dune,Edge,Pasture,Yard or Garden

Cytisus scoparius is well adapted to dry sandy soils and grows well in full sunlight. It can be found along roadsides, coastal sites, disturbed sites, pastures and dry scrubland.


THREATS

Cytisus scoparius has been recognized as a pest weed in the interior valleys along the West coast of the U.S. since the 1920s. It is very competitive in areas with poor soils because of its association with nitrogen fixing bacteria. It has demonstrated the ability to form dense monospecific stands along roadways and waterways. It can also invade native grasslands, pastures and cultivated fields, making it an agricultural pest. To date, Cytisus scoparius has not had the level of negative impact in New England that it has had in the western U.S. and Canada.


DOCUMENTATION NEEDS

Documentation required: A specific photograph or mounted snippet of a branch with flowers.
Best time for documentation: Summer, fall, winter.


ADDITIONAL INFORMATION

Integrated Taxonomic Information System
Taxonomic information about the species

The PLANTS database
General information and map

University of Connecticut Plants Database
Images and descriptive information

Virginia Tech Dendrology
Images and brief description

Redwood National Park

National Invasive Species Information Center
Additional links


REFERENCES

Bailey, L. H.  1949.  Manual of Cultivated Plants.  Macmillan, New York.

Bossard, C.C. 1991. The role of habitat disturbance, seed predation, and ant, dispersal on establishment of the exotic shrub Cytisus scoparius in California. The American Midland Naturalist 126, 1-13.

Bossard, C.C. 1993.  Seed germination in the exotic shrub Cytisus scoparius (Scotch broom) in California. Madrano 40, 47-61.

Bossard, C. 1996. Cytisus scoparius, p.52. In Randall, J.M. and J. Marinelli. [eds.].  Invasive Plants: Weeds of the Global Garden. Brooklyn Botanic Garden Inc., New York.

Bossard, C.C. and M. Rejmanek. 1994. Herbivory, growth, seed production, and resprouting of an exotic invasive shrub Cytisus scoparius. Biological Conservation 67 (3), 193-200.

Britton, N. L. and A. Brown.  1970.  An Illustrated Flora of the Northeastern United States vol. 2.  Dover Publications Inc., New York.

Carter, K. and A. Signor. 2000. Controlling broom (Cytisus scoparius (L.) Link) in native forest ecosystems. Plant Protection Quarterly 15, 165-166.

Fernald, M.L. 1950. Gray's Manual of Botany 8th ed. American Book Co., Boston.

Fire Conference 2000.  Proceedings of the Invasive Species Workshop: The Role of Fire in the Control and Spread of Invasive Species. The First National Congress on Fire Ecology, Prevention, and Management.  Tall Timbers Research Station, Miscellaneous Publication No. 11. 

Gleason, H.A. and A.C. Cronquist.  1991.  Manual of Vascular Plants of the Northeastern United States and Adjacent Canada. 2nd ed.  New York Botanical Garden, Bronx, New York.

Holmgren, N.H. 1998. Illustrated Companion to Gleason and Cronquist's Manual.  New York Botanical Garden, Bronx, New York.

Isaacson, D.L. 2000. Impacts of broom (Cytisus scoparius) in western North America. Plant Protection Quarterly 15, 145-148.

Magee, D.W and H.E. Ahles. 1999.  Flora of the Northeast. University of Massachusetts Press, Amherst.

Newcomb, N. 1977.  Newcomb's Wildflower Guide.  Little Brown, Boston.

Peterson, R.T. and M. McKenny. 1968. A field Guide to Wildflowers of Northeastern and North-central North America.  Houghton Mifflin, Boston.

Peterson, D. and R. Prasad. 1998 The biology of Canadian weeds. 109. Cytisus scoparius (L.) Link. Canadian Journal of Plant Science 78, 497-504.

Robinson, B.J.  1908.  Gray's New Manual of Botany  7th ed.  American Book Co., New York, NY.

USDA, NRCS.  2001.  The PLANTS Database, Version 3.1. (http://plants.usda.gov).  National Plant Data Center, Baton Rouge, LA 70874-4490 USA.