Yellow Burrweed

Amsinckia calycina (Moris) Chater, Amsinckia intermedia Fischer & C.Meyer, Amsinckia lycopsoides (Lehm.) Lehm.

Synonyms - Amsinckia hispida, Amsinckia angustifolia and Lithospermum hispidum are synonyms for Amsinckia calycina. Amsinckia hispida is occasionally synonymous with Amsinckia intermedia. This is a difficult genus with many intermediate forms.

Family: - Boraginaceae.


Amsinckia is named after Wilhelm Amsinck 1752-1831 who developed the botanical gardens in Hamburg.

Yellow Burrweed refers to the flower colour and the burr like nature of the sepals surrounding the seed.

Other Names:

Amsinckia, Bugloss Fiddleneck (A. lycopsoides), Common Fiddleneck (A. intermedia), Fiddleneck, Hairy Fiddleneck (A. calycina), Iron weed, Tar weed, Yellow Burrweed, Yellow Burr-weed, Yellow Forget-me-not.


An erect, winter annual, stiffly hairy to almost hairless herb to 1 m tall with orange to yellow trumpet shaped flowers in spring on an erect shoot arising from a rosette of narrow, hairy leaves.



Two. Y shaped. Tips rounded. Few fine hairs and pimples on upper surface.

First leaves:

Erect and covered with stiff hairs.


Alternate. Lower leaves form a rosette. Upper leaves smaller and clasp stem.

Stipules -

Petiole - Short on the lower leaves to none on the upper leaves.

Blade - 20-200 mm long by 6-40 mm wide. Spear shaped. Covered in stiff, intermixed long and short hairs. Acute to obtuse tips. Edges entire.

Stem leaves - Smaller. Clasp stem. Alternate.


Up to 60cm. Branched. Elongate in late winter. Covered in stiff, intermixed long and short hairs.

Flower head:

Dense cyme that elongates when in fruit. At the ends and along one side of curved branches. The flower stem is tightly coiled initially and straightens as flowering progresses. 100 -250 mm long.


Bracts - none.

Ovary - 4 lobed. Style twice as long as the ovary with a cut off slightly 2 lobed stigma.

Sepals - 5 bristly, spear shaped to parallel sided segments. About 3-6 mm long and lengthening to 10 mm when in fruit.

Petals - 5 yellow/orange petals fused to form a trumpet shape. Small.

A. calycina is pale yellow, has an open corolla throat, hairless and 5-10 mm long by 2-4 mm wide. The corolla is slightly longer than the calyx.

A. intermedia is orange yellow, has an open corolla throat, hairless and 5-15 mm long by 6-10 mm wide. The corolla is obviously longer than the calyx.

A. lycopsoides has intruding hairy pouches in the corolla throat.

Stamens - inserted above the middle of the tube.

Anthers -


1-4 nutlets, enclosed in the sepals.


Actually a nutlet with one seed. Brown to black, 3 sided pyramid shaped, wrinkled with warts. 2-3.5 mm long. Attached to the conical receptacle by a narrow areole.


Stout taproot with many laterals.

Key Characters:


Life cycle:

Annual. Germinates after the first rains in autumn/winter with successive germinations after rainfall events in the cooler months. Often four or more waves of emergence. The seedlings grow quickly and are competitive. They form a rosette and the flowering stem emerges in mid winter. Flowering starts in August and continues through spring for around 8 weeks. Flowers develop from the base of the tightly coiled flowering stem and progresses upward as the stem uncoils. This results in a range of seed maturity times. The plant dies off as temperatures rise in early summer.



By seed.

Flowering times:

September to November.

Seed Biology and Germination:

Produces up to 1600 seeds per plant. The longevity of the seed in the field is unknown but is probably quite short with most seed lasting less than 2 years.

Vegetative Propagules:


Hybrids between the three species have been found.


Population Dynamics and Dispersal:

Spread by;
  1. spiny dried flower heads clinging to wool, fur and clothing.
  2. seed contaminating cereal grain, hay and fodder.
  3. agricultural machinery including harvesters, seed graders, and hay making equipment.
  4. viable seed passes through sheep. Birds eat the seeds but the importance of this as a dispersal mechanism is not known.
Origin and History:

Amsinckia calycina - South America and southern North America. Chile. Naturalised in the Mediterranean region.

Amsinckia intermedia - Western North America.

Amsinckia lycopsoides - Central North America.



Amsinckia intermedia Has not been recorded for WA. The other species are occasionally found in the eastern wheatbelt.

Found in SA in 1858, VIC in 1893, NSW in 1903 and WA in 1936.



Temperate regions.


A. intermedia prefers loamy or sandy soils. Other species occur on a wide range of soil types.

Plant Associations:

Associated with cultivation. Prefers open situations.



Despite its toxicity, Amsinckia is an useful source of forage in semi arid Arizona.


Weed of roadsides, fallows, pastures, lucerne and cereals. Causes loss of cereal yield, taints flour and fragments of the black seed coat discolours flour.

Contaminates commercial ryegrass seed.

Contaminates wool.

Weed of vineyards, orchards and range lands overseas.


Seeds are poisonous to stock causing severe liver damage.

Toxic to pigs and horses in the USA. Probably toxic to cattle.




Declared plant in NSW, VIC and WA.

Management and Control:

Cultivation and blade ploughing are effective but need to be repeated for successive germinations. A number of selective herbicides are available for selective use in cereals and other crops. Mowing and slashing before seed set can effectively reduce soil seed banks. Spray grazing is effective in pasture situations.


More than 25 plants/m2 is usually worth spraying. 90 plants/m2 have reduced wheat yields by 48%. Wheat yield responses of 150% have been recorded. Its main effect appears to be reduction in tiller number of the cereals indicating that is a strong competitor for nitrogen and should be removed from the crop as early as possible.

Eradication strategies:

Herbicide resistance:

Resistant to 2,4-D.

Biological Control:

Bio control is being investigated in the USA.

Related plants:

Forget-me-nots Myosotis sylvatica

Comfrey Symphytum spp.

Plants of similar appearance:

Corn gromwell, Paterson's curse, Heliotrope.


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Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P716-717. Diagram.

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). p306-307.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P360-361. Photo.

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). p???.

Gardner, G.A. and Bennetts, H.W. (1956). The toxic plants of Western Australia. (West Australian Newspapers Ltd, Perth). P158-159. Diagram.

Gilbey, D. (1989). Identification of weeds in cereal and legume crops. Bulletin 4107. (Western Australian Department of Agriculture , Perth). p68. Photos.

Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne). p???.

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #80.1, #80.2, #80.3.

Muenschner p356n

Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious weeds of Australia. (Inkata Press, Melbourne). 322-325. Photos.

Wilding, J.L. et al. (1987). Crop weeds. (Inkata Press, Melbourne). p66. Photos. Diagrams.


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