A grey green, variably hairy, annual or biennial, bushy plant with deeply lobed leaves and 4-petalled, yellow flowers from February to November with a flush in spring. It has very long (40-120 mm) slender pods at right angles to the stem. The middle stem leaves are usually arrow shaped.
Description:
Cotyledons:
Two, lean against each other(incumbent). Oval, 5-8 mm long, tip slightly indented on a 5-8 mm long stalk(petiole). Hairless or with a few long hairs. The seedling has a short hypocotyl and no epicotyl.
First Leaves:
Arise singly, oval with an acute tip and toothed edges, 8-12 mm long, on an 8-12 mm long petiole. Few longish hairs. Later leaves are longer and more deeply lobed.
Leaves:
Forms a short lived basal rosette of leaves, 200-300 mm in diameter that wither or are carried up the stem as it elongates.
Stipules - None.
Petiole - 50-70 mm long on basal leaves.
Blade - 55-200 mm long by 20-45 mm wide, deeply lobed, usually 4 pairs of lobes, end lobe is larger than the triangular side lobes that tend to point towards the base of the leaf. All lobes have erect or spreading ear like appendages at their bases. Tip rounded to pointed. Base tapered to squarish. Leaves dry up and fall off with age. Few hairs.
Stem leaves - Alternate. Similar to rosette leaves. Lower ones, 50-200 mm long by 20-45 mm wide, stalked with 1-4 pairs of lobes with fine hairs on the upper and lower surfaces. Middle ones arrow shaped, often with two, slender basal lobes and variably hairy. Upper ones often not lobed and hairless.
Stems:
Grey green, slender, erect, round, solid with a pithy core, up to 1300 mm tall and usually woody. Hairy near base, often hairless near top. Fine, soft, bent back hairs on the young stems. Much branched with the branches at 45 degrees to the main stem. Wiry when dry.
Flower head:
Flowers borne in clusters near the tops of stems in an elongated paniculate racemes. Stems elongate as pods form and new flowers are added to the cluster on top.
Flowers:
Yellow, 3-10 mm diameter on spreading stalks(pedicels).
Ovary - Stigma entire and stalkless.
Sepals - 4, erect, 3-5 mm long, hairy. Alternate with the petals.
Petals - 4, pale yellow, 5-10 mm long.
Stamens -
Anthers -
Fruit:
40-120 mm long by 1-1.5 mm wide, cylindrical, slender, rigid, 2 celled capsule, curved or straight on 3-10 mm long stalks(pedicels) that are almost as thick as the fruit. Sticks out from stem at 45-900. Sparsely hairy when young. Valves thick walled and 3 nerved. Opens from base to release seed when ripe. Single row of seeds. About 60 seeds per cell or 120 per pod.
Seeds:
Small, brown, narrowly egg shaped to oblong and not flattened, 1 mm long by 0.6 mm wide. Rounded on the back and often indented on the inner two faces. Surface finely dimpled with longitudinal rows of tiny warts and hairless. Many seeds that are arranged in 1 row.
Roots:
Taproot.
Key Characters:
Cotyledons incumbent.
Hairs simple or absent.
Leaves smooth and hairless or with scattered hairs.
Petals pale yellow, 5-10 mm long, not twisted, rarely more than twice as long as the sepals.
Pod spreading, 60-120 mm long by 1-1.5 mm wide, slender, cylindrical or terete, 3 nerved, dehiscent, not beaked and persistent style very short, at least 3 times long as broad, seeds 1 rowed.
Pedicels short, usually less than 8 mm long, almost as thick as the fruit.
Valves with prominent midrib, compressed from the back.
From J.M. Black, N.T. Burbidge and B.L. Rye.
Biology:
Life cycle:
Annual or biennial. Seeds germinates from autumn to winter with some in spring. It grows mainly in autumn and spring. Flowers mainly in spring but odd flowers may occur at almost any time. Seed shed in early summer. It usually dies off in summer but some plants may survive into their second season in moist areas.
Physiology:
Reproduction:
By seed.
Flowering times:
February to November but mainly in spring
September to December in SA.
March to October with a flush in August to October in Perth.
Mid winter to early summer in WA.
Seed Biology and Germination:
Vegetative Propagules:
Hybrids:
Allelopathy:
Population Dynamics and Dispersal:
Produces large amounts of seed.
Spread by seed.
Origin and History:
Southern Europe. Mediterranean. North Africa. Western Asia.
Distribution:
ACT, NSW, NT, QLD, SA, TAS, VIC, WA.
In all parts of Tasmania.
Widespread in the wheat belt of WA.
Habitats:
Climate:
Temperate. Mediterranean.
Soil:
Most soil types.
Plant Associations:
In Bimble Box, Black Box and Bladder Salt Bush communities.
Significance:
Beneficial:
Does not host Root Lesion Nematode (Pratylenchus neglectus or thornei) (63).
Detrimental:
Weed of crops, pastures, orchards, fallows, roadsides, stock yards, stock camps, swamp margins, grazed woodlands and disturbed areas.
Causes yield reductions due to competition.
Wiry stems blocks cereal harvesters.
Relatively unpalatable.
Toxicity:
Not recorded as toxic.
Legislation:
None.
Management and Control:
Thresholds:
Eradication strategies:
Manually remove isolated plants.
Prevent seed set. Spray small infested areas with 500 mL/ha of Brodal in winter each year.
Most of the Brassicaceae weeds have dormant seeds that continue to germinate throughout the season and for several years. They often mature and set seed very quickly. Manual removal is effective but must be done at least every 8-10 weeks. Once pods are formed, seed will often mature even if the plant has been uprooted. Soil disturbance often leads to a flush of seedlings.
Many are somewhat unpalatable, so grazing only offers partial control. They often flourish in undergrazed, sunny areas.
In bushland situations, fairly selective control can be achieved with 100 mL spray oil plus 0.1 g Eclipse® or 0.5 g Logran® in 10 L water. 5 mL Brodal® is often added to this mix to provide residual control of seedlings. Spray the plants until just wet from the seedling stage up to pod formation.
Isolated plants should be removed manually and burnt if flowering or seeding and a 10 m buffer area sprayed with 10 mL Brodal® in 10 L water.
500 mL/ha of glyphosate(450g/L) can be used at flowering to reduce the seed set of most species on roadsides without causing significant damage to most native plants.
Wick application with 1 part glyphosate(450g/L) in 2 parts water or overall spraying with 100 mL glyphosate(450g/L) in 10 L water provides reasonable control of most species though Wild Radish tends to regrow.
Herbicide resistance:
Some populations are resistant to Group B (sulfonyl urea) herbicides.
Biological Control:
Related plants:
African Turnip weed (Sisymbrium thellungii)
Hedge Mustard (Sisymbrium officinale) is almost identical in the seedling stage. At the rosette stage it has a an short and rounded end lobe on the leaf. When mature it has a smaller flower and shorter pod that is held close to the stem.
London Rocket (Sisymbrium irio) is similar but has more and shorter pods that are more closely clustered.
Smooth Mustard (Sisymbrium erysimoides)
Sisymbrium runcinatum
Plants of similar appearance:
Wild Radish, Wild Turnips and Mustards.
References:
Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P137 139. Diagram. Photos.
Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P374. Diagram.
Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P181, 185. Diagram.
Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P335. Photo.
Gilbey, D. (1989). Identification of weeds in cereal and legume crops. Bulletin 4107. (Western Australian Department of Agriculture , Perth). P16. Diagram. Photos.
Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P122. Photo.
Hyde-Wyatt, B.H. and Morris, D.I. (1975). Tasmanian weed handbook. (Tasmanian Department of Agriculture, Hobart, Tasmania). P46-47. Diagrams.
Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).
Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #1137.4.
Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P169.