Stagger weed

Stachys arvensis (L.) L.

Family: - Lamiaceae.


Stachys is the Greek for an ear of corn or a spike bearing plant and is derived from the Latin spica meaning spike and refers to the spike type flower head.

Arvensis is from the Latin arvum meaning cultivated field and refers to the plants association with cultivation.

Stagger weed because it produces staggers in stock that graze it.

Other names:

Field Stachys

Field Wound Root

Hedge Nettle

Mint Weed.


A sparsely hairy, low lying annual herb with a slightly minty aroma, square, weak stems, opposite, wrinkled, deeply veined, heart shaped leaves with rounded teeth and small, purple, 2 lipped flowers from April to October.



Two. Round to heart shaped blade, 5-8 mm long, tip indented, base indented. A few hairs on the upper surface only. Stalk 4-6 mm long with a few hairs. The seedling has a hypocotyl and epicotyl.

First Leaves:

Paired, oval 10-14 mm long with 8-12 mm long, hairy petiole. Tip round. Fine hairs on upper surface and a few mainly on veins underneath. Edges usually with 3-4 rounded lobes on each side with the basal lobe being the smallest.


Opposite, paired. Successive pairs at right angels to each other. Unpleasant mint smell when crushed. Forms a basal cluster of leaves rather than a rosette.

Stipules - None.

Petiole - Longer on the lower leaves. Hairy.

Blade - Pale dull green, egg shaped with rounded teeth on the edges, 5-45 mm long by 4-26 mm wide, crinkled, veins indented. Base slightly indented or flat. Obtuse tip. Scattered, long, multicellular hairs on both surfaces.

Stem leaves - Upper stem leaves 30 mm long with no stalk. Hairs on both surfaces especially along the veins.


Initially erect but drooping with age with the tips bent upwards, weak, soft, up to 300 mm, square, solid, branched. Hairy with spreading long hairs. Variable in growth habit.

Flower head:

Leafy spike of clusters of 2-6, almost stalkless flowers in rings around the stem in leaf axils with 2 leaf like bracts underneath. Lower clusters are well spaced, upper ones close together.


Violet, blue or pink, small, tubular.

Bracts - Tiny, parallel sided.

Ovary -

Calyx - Tubular, narrowly bell shaped, 5-7 mm long, with 5, narrowly triangular lobes as long as the tube, 5-10 nerved. Lobes often purplish and with a short point where the midrib sticks out. Long multicellular and short glandular hairs.

Petals - Violet, blue or pink, tubular and 2 lipped, 5-8 mm long, a little longer than the calyx. Upper corolla lip hooded over the stamens, erect. Lower lip spreading, 3 lobed

Stamens - 4, lower pair longer, more or less stick out from the corolla tube

Anthers - Smooth and hairless, 2 celled, the cells initially divergent, finally placed end on end.


1-4, dark brown to black, egg shaped nutlets, 2 mm long, finely dimpled or warty, rounded at the top.


Enclosed in fruit. Surface hairless.



Key Characters:

Green, sparsely hairy annual herb, not strongly scented.

Leaves and flowers opposite.

Inflorescence of few flowered verticillasters.

Corolla with 2 distinct lips, upper corolla lip hooded.

Calyx almost equally 5 lobed, 5-10 nerved, lobes triangular, not spiny.

Stamens 4, more or less exerted from the corolla tube

Anthers glabrous, 2 fertile cells, the cells finally placed end on end.

Nutlets rounded at summit.

From J.M. Black and J.R. Wheeler.


Life cycle:

Annual. Seeds germinate from autumn to spring and it grows mainly from autumn to spring. It flowers in spring and dies in summer.



By seed.

Flowering times:

Spring in western NSW.

Most of the year in SA.

August to October in Perth

Winter and early spring in WA.

Seed Biology and Germination:

Vegetative Propagules:




Population Dynamics and Dispersal:

Spread by seed.

Origin and History:




Occurs in most parts of Tasmania.



Temperate. Mediterranean.


Sands and other soils.

Plant Associations:





Weed of pastures, crops, vegetables, stubbles, cultivation, gardens, lawns, roadsides, granite outcrops, urban bushland and disturbed areas.

It can be strongly competitive.


May cause staggers or shivers in sheep, cattle, horses and pig that eat quantities of the mature seed bearing plant or seeds. It may be transferred through milk to the lambs. Young sheep are more susceptible than old. Young plants and old plants that have shed their seed are not as toxic as seed bearing plants.

It may also contain sufficient nitrate to cause nitrate poisoning.


Often only seen when stock are stressed 2-40 days after consuming the plant. Most reports are from August to October. Staggers, shivering, lagging behind the mob, reluctance to move. If forced to move they may die. Cattle may also show dullness, diarrhoea and apparent blindness. Pigs may show weakness of the hind or forequarters.


Animals usually recover completely in 2-14 days after removal from the infestation.

Don't graze seed bearing areas of the plant. Offer affected mobs alternative feed for 3 or 4 days before moving them.



Management and Control:


Eradication strategies:

Prevent seed set.

Herbicide resistance:

Biological Control:

Related plants:

Woolly Stachys (Stachys byzantina) is perennial and much hairier.

Plants of similar appearance:

Deadnettle (Lamium amplexicaule) has an oval cotyledon and a distinctive semi circular notch at the base and long, thin petioles that are at right angles to the cotyledon and first leaf.

Creeping Speedwell (Veronica persica) is similar in the seedling stage but has more spoon shaped cotyledons and first leaves, older leaves are much more divided.

Ivy Leaf Speedwell (Veronica hederifolia) is similar in the seedling stage but the cotyledon is more oval and the first leaves have a shiny surface, older leaves are much more divided.



Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P182. Photos.

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P741. Diagram.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P576. Photo.

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P387. Fig 23.

Gardner, G.A. and Bennetts, H.W. (1956). The toxic plants of Western Australia. (West Australian Newspapers Ltd, Perth). P161-163. Diagrams.

Gilbey, D. (1989). Identification of weeds in cereal and legume crops. Bulletin 4107. (Western Australian Department of Agriculture , Perth). P56. 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). P172-173. Photo.

Hyde-Wyatt, B.H. and Morris, D.I. (1975). Tasmanian weed handbook. (Tasmanian Department of Agriculture, Hobart, Tasmania). P82-83. 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). #1160.1.

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). P566. Diagrams.

McBarron, E.J. (1983). Poisonous plants. (Inkata Press, Melbourne). P45. Diagram.

Wilding, J.L. et al. (1987). Crop weeds. (Inkata Press, Melbourne). P124. Diagrams. Photos.


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