African Turnip Weed

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Quick Facts

Quick facts

  • African Turnip Weed (Sisymbrium runcinatum) is a prostrate annual herb to 0.5 m high.
  • It is similar to other cruciferous weeds so care should be taken with its identification.
  • It is a potentially significant weed in cropping situations but is as yet is only naturalised in Western Australia.

What Does It Look Like?

What is it?

African Turnip Weed (Sisymbrium runcinatum) is an annual herb that grows up to 50 cm tall. The stems arise from a basal rosette of leaves and either lie flat against the ground or grow obliquely upwards. The basal leaves are deeply and jaggedly lobed with the lobe tips pointing backwards to the leaf base. The upper leaves are similar in appearance to the basal leaves but diminish in size along the stems.

The flowers occur in long, loosely-flowered racemes (elongated stem with flowers produced along its length). There is a small, leaf-like bract occurring just below each flower. The flowers consist of four, white to yellow petals with each petal up to 3.5 mm long.

The fruits are long and narrow (1–3.5 cm long, 1–2 mm wide) and densely hairy. The short stalks that attach the fruits to the stem are held erect, causing the base of the fruits to be pressed against the stem. The seeds are small (about 1 mm diameter) (Hewson 1982; Rich 1991; Hussey et al. 2007).

For further information and assistance with identification of African Turnip Weed contact the herbarium in your state or territory.

Flower colour

  • Yellow
  • White

Growth form (weed type/habit)

Herb

Where it currently grows? Preferred habitat

In Western Australia, African Turnip Weed is found as a localised weed of road verges and granite rocks in the southern part of the state (Hussey et al. 2007). African Turnip Weed has been recorded growing on a range of soil types including clay, sand/loam and loam. It has been collected from various habitats including cropland, pasture, roadsides, open shrubland and eucalypt woodland (Western Australian Herbarium 2007).

Are there similar species?

African Turnip Weed can be distinguished from other species of Sisymbrium by the presence of bracts (modified leaves) surrounding the flowers and by its small, densely hairy, curved fruits (up to 3.5 cm long) (Hewson 1982; Hussey et al. 2007). However, in Australia, there are numerous weedy cruciferous species that are superficially similar in appearance to African Turnip Weed. Various weed guides, including Richardson (2007), Auld & Medd (1996) and Hussey et al. (2007 or the Herbarium in your state or territory should be consulted for further information on differentiating between these species.

Why Is It A Weed?

What are its impacts?

Agriculture and Native ecosystems: African Turnip Weed is recorded as a weed of crops, pastures and in native bushland in Western Australia (Western Australia Herbarium 2007).

How does it spread?

African Turnip Weed is an annual species, hence reproduction occurs by seed. Although no published information could be found on the dispersal mechanisms used by African Turnip Weed, it is assumed that it spreads in the same manner as other similar weedy cruciferous species such as Wild Radish (Raphanus raphanistrum) and Sand Rocket (Diplotaxis tenuifolia).

Theses species spread by water, especially where plants grow in riparian habitats and on steep terrain where erosion and runoff occurs. Contaminated soil, fodder, vehicles and other equipment are potential vectors for seed transport. Seeds may also be readily dispersed along roadsides during roadside maintenance works. Dispersal via contaminated agricultural produce is also a potential means of spread (Parsons & Cuthbertson 2001).

What is its history in Australia?

The earliest records of African Turnip Weed in Australia are two herbarium collections taken from Mullewa and the Yilgarn Range in Western Australia in 1960 (Western Australian Herbarium 2007). It is not known how or why African Turnip Weed was introduced into Australia.

How To Manage It?

Best practice management

There is currently no information available on the control of African Turnip Weed in Australia.

Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au 

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

African Turnip Weed is an annual that flowers from August to September in Western Australia (Western Australian Herbarium 1998-) and has been found to have a persistent seed bank in Mediterranean areas of the northern hemisphere (Ortega et al. 1997).

Where Is It Found?

Which states and territories is it found?

WA

What areas within states and territories is it found?

In Australia, African Turnip Weed is only known to be naturalised in Western Australia where, it occurs in the Coolgardie, Yalgoo, Avon Wheatbelt and Geraldton Sandplains regions (Western Australian Herbarium 1998 -).

Where does it originate?

African Turnip Weed is native to south-western Europe (Ball 1996) and northern Africa (African Flowering Plants Database 2007).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

NSW, WA

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Sisymbrium runcinatum

Other scientific names (synonyms)?

 

Does it have other known common name(s)?

African Turnipweed

Bibliography

Australian Plant Census (2011) available at: Vascular Plants APNI (biodiversity.org.au).

African Flowering Plants Database (2007) Conservatoire et Jardin botaniques de la Villle de Genève and South African National Biodiversity Institute, Pretoria.

Auld, B.A. & Medd, R.W. (1996) Weeds: an Illustrated Botanical Guide to Weeds of Australia. Inkata Press, Sydney.

Ball, P.W. (1996) Sisymbrium. In Tutin, T.G., Burges, N.A., Chater, A.O., Edmondson, J.R., Heywood, V.H., Moore, D.M., Valentine, D.H., Walters, S.M. & Webb, D.A. (eds): Flora Europaea, Volume 1, Second Edition. Cambridge University Press, Cambridge, New York, Melbourne: 318-321.

Hewson, H.J. (1982) Brassicaceae in George, A.S. (Ed), Flora of Australia Volume 8-Lecythidales to Batales. Australian Government Printing Service, Canberra.

Hussey, B.M.J., Keighery, G.J., Dodd, J., Lloyd, S.G. & Cousens, R.D. (2007) Western Weeds: A Guide to the Weeds of Western Australia, 2nd Edition. The Weeds Society of Western Australia, Victoria Park. 

Ortega, M., Levassor, C. and Peco, B. (1997). Seasonal dynamics of Mediterranean pasture seed banks along environmental gradients. Journal of Biogeography 24: 177-195. 

Parsons, W.T. and Cuthbertson, E.G. (2001). Noxious Weeds of Australia. CSIRO Publishing, Victoria. 

Rich, T.C.G. (1991) Crucifers of Great Britain and Ireland. Botanical Society of the British Isles, London. 

Richardson, F.J., Richardson R.G. & Shepherd R.C.H. (2006) Weeds of the South-East: An Identification Guide for Australia. R.G. Richardson and F.J. Richardson, Meredith.

Western Australian Herbarium (1998-). FloraBase - The Western Australian Flora. Department of Environment and Conservation. Available at: Taxon Profile of Sisymbrium runcinatum DC. | Florabase (dbca.wa.gov.au)

Western Australian Herbarium (2007) Data provided by the Western Australian Herbarium on 10 December 2007.

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