Species: Stachys arvensis
Family: Lamiaceae (Mint family).
Common names: Stagger weed, Corn woundwort, Field stachys, Field wound root, Field woundwort, Hedge nettle, Mintweed, Woundwort.
Confused with:
Deadnettle (Lamium amplexicaule) and
dwarf nettle (Urtica urens). These can be distinguished by:
•
Seedlings – dwarf nettle leaves are dark green with sharply serrated edges. Stems are reddish towards the base. Stagger weed leaves are yellowish-green and egg-shaped, longer than they are wide. Stagger weed leaves have a minty smell when crushed. Deadnettle are darker green than stagger weed and more of a pointed-fan shape, wider than they are long.
•
Flowers – Dwarf nettle flower are white and very small. The flower head is green. Stagger weed pale pink to pale lilac. Deadnettle flowers are purple to bright red.
Description: Seedling leaves – are round, 3 - 5 mm in diameter and yellowish-green with short stalks. The first true leaves are broadly egg-shaped, with an indented base where they meet the leaf stalk. Leaves are lightly covered in hairs, and are corrugated by central and lateral veins. The leaf margins are roundly toothed.
Older leaves - are yellowish-green, opposite and on stems less than 20 mm long. New branches arise from the leaf axils. Leaves are 8 – 45 mm long and 4 – 32 mm wide. Leaves are lightly covered in hairs, and are corrugated by central and lateral veins. The leaf margins are roundly toothed.
Plants – a semi-erect annual to 35 cm high, yellowish-green in colour. Stems are slender and 4-angled, 15 – 45 cm high and covered with spreading hairs. Plants emit a mint-like odour when crushed.
Flowers – are white to pale pink, 5 – 7 mm long, borne in clusters of 2 – 6 in the forks of the leaves.
Seeds – 1 – 4 seeds develop in a “cup” in the leaf forks. Seeds are dark brown and lightly mottled, 2 – 2.5 mm long.
Lifecycle/Biology: An annual plant that emerges in autumn and winter, flowering in winter and spring.
Ecology: A common weed of cereal cops and winter fallows, and will established in pastures.
The problem: Stagger weed is a minor pest of cereal crops and winter fallows, irrigation channels and waste areas. Stagger weed can be eaten by livestock and will cause staggers. The poison is cumulative and the effects become apparent in stressed stock. Stagger weed can kill stock.
Distribution: A widespread weed, occurring in all states, except the Northern Territory.
Origin: An introduced species from Europe and the Mediterranean region.
References: Plants of Western New South Wales, p. 576 - 577.
Crop Weeds of Northern Australia, p. 84 - 85.
Compiled by: Graham Charles
