''Stachys arvensis'' is a species of flowering plant in the

mint family The Lamiaceae ( ) or Labiatae are a family of flowering plants commonly known as the mint, deadnettle, or sage family. Many of the plants are aromatic in all parts and include widely used culinary herbs like basil, mint, rosemary, sage, sav ...

known by the common names field woundwort and staggerweed. It is native to Europe,

Western Asia West Asia (also called Western Asia or Southwest Asia) is the westernmost region of Asia. As defined by most academics, UN bodies and other institutions, the subregion consists of Anatolia, the Arabian Peninsula, Iran, Mesopotamia, the Armenian ...

, and North Africa. It is known on other continents as an

introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...

and widespread

weed A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. Pla ...

Description

Field woundwort is an annual herb with branched, square stems up to 45 cm long, growing with a sprawling or erect habit. The stems are pale green and covered with patent, sparsely glandular hairs up to 2 mm long. Plants are easily uprooted to reveal a mass of short, white, fibrous roots at the base of the plant and sometimes along any horizontal stems close to the base. The leaves are arranged in opposite,

decussate Decussation is used in biological contexts to describe a crossing (due to the shape of the Roman numeral for ten, an uppercase 'X' (), ). In Latin anatomical terms, the form is used, e.g. . Similarly, the anatomical term chiasma is named aft ...

pairs, with no stipules, and petioles of up to 4 cm long; the blade is simple and oval, up to 4 cm long, with a truncate base and between 7 and 12 rounded teeth per side. They are dull, medium green on the upper surface and paler beneath, hairy on both sides. The

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

consists of a terminal spike with up to 8 false whorls (actually two opposite clusters that look like a whorl) of 4 to 7 flowers, each with a short pedicel of up to 1.5 mm. The whorls are subtended by a pair of leaf-like bracts which are stalked at the base of the inflorescence, becoming sessile towards the top of the plant. There is also one tiny bracteole at the base of each cluster of flowers. The lower whorls are widely spaced, but the upper ones are more crowded towards the tip of the plant. The flowers are zygomorphic with a 5 lobed calyx tube 5 to 7 mm long, and two lipped corolla 6 to 8 mm. The upper lip is entire and the lower lip is three lobed, with the central lobe much larger. It can be white, pink or purple.

Habitat and ecology

It grows in many types of habitat, including disturbed areas, and often in moist spots.

Taxonomy

Stachys arvensis was described by Linnaeus in 1763. The common name staggerweed is because the plant is poisonous to livestock and causes livestock to stagger around.

Uses

As its common name 'field woundwort' suggests, this herb has been used since Roman times in healing wounds, and its seeds, scattered by Roman soldiers, mark the lines of Roman roads.Carlton Reid (2014). "Roads Were Not Built for Cars". Island Press. p. 39 Its close relatives hedge woundwort and marsh woundwort are also used to treat wounds.

References

External links

Jepson Manual Treatment
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Washington Burke MuseumPhoto gallery
arvensis Flora of Western Asia Flora of North Africa Flora of Europe Taxa named by Carl Linnaeus {{Lamiaceae-stub