Family: Brassicaceae (Mustard Family)
Duration and Habit: Annual Herb
Bastard cabbage is an annual, many-branched, herbaceous plant that grows from 1 to 5 feet or more in height. It has a robust taproot that can become quite large and deep-rooted. Leaves are deep green, lobed and wrinkled, and sometimes have a reddish cast. The terminal lobe is larger than the lateral lobes, especially on the basal leaves. Younger leaves growing higher up on the plant are less lobed and more elongated. Bastard cabbage typically flowers from early spring into summer, bearing clusters of small, showy yellow flowers at the tips of its branches, resembling those of broccoli and cabbage. Bastard cabbage can be identified more easily and certainly by its unusually shaped fruit - a two-segmented seed capsule, called a silique. The seed capsule is stalked, with a long beak at the tip, and contains 1-2 seeds. The seeds are oval-shaped, dark brown, smooth, and tiny (about 1/16-inch).
Two subspecies of this plant are recognized: R. rugosum ssp. rugosum and R. rugosum ssp. orientale. Bastard cabbage is also known as turnip-weed, common giant mustard, ball mustard, wild turnip, wild rape and tall mustard-weed. It is designated a terrestrial noxious-weed seed in the state of Texas.
Ecological Threat: Bastard cabbage is an early successional plant that develops a broad, robust mass of basal leaves, which allows it to successfully outcompete native plant species. In some places, it forms a monoculture (a vegetative cover of mostly one species). Annual bastard-cabbage has long been established on agricultural fields, roadsides, and disturbed lands and is becoming invasive in natural areas such as open forests and along streams.
Biology & Spread: Bastard cabbage seeds germinate early in the growing season (late fall or early winter) and quickly cover the ground with a blanket of leafy rosettes (circles of leaves at ground level). These dense rosettes block sunlight from reaching seeds and seedlings of native plants.
History: It is uncertain how bastard cabbage was introduced into the U.S. It appears to spread through contaminated grass seed mixes or mulching materials. Seeds are similar in size to those of wheat and rye, weed seed screens may fail to remove it from grass seed mixes.
U.S. Habitat: Bastard cabbage grows mostly in open sites on disturbed soils, including roadsides, ditches, and agricultural areas.
U.S. Nativity: Introduced to U.S.
Native Origin: Native to southern European (i.e. France, Portugal, Spain, Albania, Bulgaria, Greece, Italy, Yugoslavia, Ukraine and southern Russia), the Azores, the Madeira Islands, the Canary Islands, northern Africa (i.e. northern Algeria, Egypt, northern Libya, Morocco and Tunisia) and western Asia (i.e. Cyprus, Iran, Iraq, Israel, Lebanon, Syria, Turkey, Armenia, Azerbaijan, Georgia, Kazakhstan and Turkmenistan).
U.S. Present: CA, HI, IL, IN, LA, MA, MO, NJ, NM, NV, NY, PA, SC, TN, TX, WI
List All Observations of Rapistrum rugosum reported by Citizen Scientists
Mowing will remove some flowers and reduce seed stocks. A preferred method is to remove the whole plant including the taproot.
Chemical control of bastard cabbage may be difficult because of its ability to ability to attain resistance to several selective herbicides.
Diggs, Jr., G. M., Lipscomb, B.L., and O'Kennon, R. J. Shinners and Mahler's Illustrated Flora of North Central Texas. Fort Worth, TX: Botanical Research Institute; 1999; p. 476.
Hashem, A., Bowran, D., Piper, T. and Dhammu, H. 2001. Resistance of wild radish (Raphanus raphanistrum) to acetolacetate synthase-inhibiting herbicides in the Western Australia wheat belt. Weed Technology 15:68-74.
Kartesz, J.T. and C.A. Meacham. 1999. Synthesis of the North American Flora. North Carolina Botanical Garden, University of North Carolina at Chapel Hill. Chapel Hill, NC. [CD]
Lemke, David E. and Worthington, Richard D. Brassica and Rapistrum (Brassicaceae) in Texas. The Southwestern Naturalist; June, 1991: pp. 194-196.
Neiman, Bill*. Personal conversation 4/9/2000. *President, Native American Seed.
Rollins, Reed C. The Cruciferae of Continental North America. Stanford, CA: Stanford University Press; 1993; p. 722.
USDA, ARS, National Genetic Resources Program. Germplasm Resources Information Network - (GRIN). [Online Database] National Germplasm Resources Laboratory, Beltsville, Maryland. (http://www.ars-grin.gov/var/apache/cgi-bin/npgs/html)
USDA Plants On-line Database. (http://plants.usda.gov)
APWG WeedUS Database
Google Search: Rapistrum rugosum
Google Images: Rapistrum rugosum
NatureServe Explorer: Rapistrum rugosum
USDA Plants: Rapistrum rugosum
Invasive Plant Atlas of the United States: Rapistrum rugosum
Bugwood Network Images: Rapistrum rugosum