Stachys arvensis
(staggerweed)

The species S. arvensis is an Old World herb species that has become naturalized in parts of the New World, and is reportedly a poison and potential seed contaminant (USDA-ARS, 2014). S. arvensis poses negative environmental, economic, and human health impacts. It is a serious weed in Austria, Brazil, and Hawaii as well as a principal and common weed elsewhere (Holm et al., 1979), and is known to be an agricultural weed in Italy and Slovenia, where it invades carrot crops (Randall, 2012). It is listed in the Global Compendium of Weeds as “agricultural weed, casual alien, environmental weed, naturalised, weed” (Randall, 2012) and is invasive to parts of Australia, China and Asia-Pacific (PIER, 2014). It causes nervous disorders to livestock (Hill, 1986).

S. arvensis is native and widespread across parts of Europe, temperate Asia, North Africa and, according to some sources, some of the Atlantic and Pacific Islands (Govaerts, 2014; PIER, 2014). As of 2008, the species was reportedly rare on the Sefton coast of northwest England (Smith, 2008), although it continues to be listed as present in the UK in Kew’s World Checklist of Selected Plant Families (Govaerts, 2014).

In several European countries including the UK, Germany, and Denmark, the species was listed as native by USDA-ARS (2014) and Govaerts (2014), but as an introduced species by DAISIE (2014).

Risk of introduction for this species appears to be mid-to-high, as it has spread beyond its native range and become naturalized, even invasive, to non-native environments (Randall, 2012; Govaerts, 2014; PIER, 2014). S. arvensis propagates by seeds and is a potential seed contaminant (USDA-ARS, 2014). As a low, creeping plant known to be a common invasive species in China, Chile, Australia, Taiwan, and parts of the Asia-Pacific (PIER, 2014), S. arvensis has been reported as a ‘serious weed’ in Austria, Brazil, and Hawaii, a ‘principal weed’ in Australia, Poland, Portugal, and Sweden, a ‘common weed’ in Argentina, England, Italy, and Turkey, and weedy in Canada, Iran, Jamaica, Jordan, Mauritius, Norway, New Zealand, Peru, and the United States  (Holm et al., 1979). It is an agricultural weed in Australia and Europe, and in Italy and Slovenia it is known to invade carrot crops (Randall, 2012; Queensland Government, 2012). Considering both its known invasiveness and weediness around the world, but also that it is responsive to herbicides (Hurford, 2007), the risk of introduction for this species is mid-to-high.  

S. arvensis is often found in waste places and disturbed areas. It is reportedly a main agricultural weed in carrot crops in Italy and Slovenia (Randall, 2012). In China and Bermuda, it has been reported to be weedy in waste areas or previously cultivated land (Britton, 1918; Flora of China Editorial Committee, 2014). It is found in the Central Brazilian Savanna and Atlantic Rainforest of Brazil (Forzza et al., 2010), while in Bolivia, it occurs in the Yungas and dry valley vegetation zones (Bolivia Checklist, 2014). In Peru, it has been observed growing in coastal regions in disturbed areas and rocky slopes (Peru Checklist, 2014). In Queensland, Australia and New Zealand, the species is a weed of gardens, fields, pastures, waste places, roadsides, river beds, and cultivation and disturbed sites (PIER, 2014; Queensland Government, 2012).

S. arvensis is an agricultural weed in Europe including Italy and Slovenia, where it invades carrot crops (Randall, 2012). In Wales, UK, S. arvensis was identified as an abundant arable weed that affects spring barley and grass crops (Hurford, 2007).

Genetics

Gametophytic count = 5; sporophytic count = 10, 18 (IPCN Chromosome Reports, 2014).

Environmental Requirements

S. arvensis is reportedly intolerant of dense shade and generally prefers soils with pH of 6.0 or less (Hurford, 2007), dry habitats and low elevations. It has been reported growing in Peru at altitudes of 0-500 m (Peru Checklist, 2014), in the Galapagos Islands between elevations of 0 and 1000 m (Vascular Plants of Ecuador, 2014) and in the Andean region of Bolivia between elevations of 1500-2000 and 2500-3000 m (Bolivia Checklist, 2014). In Hawaii the species is reportedly naturalized at low elevations up to 1200 m with dry, disturbed habitats (PIER, 2014). It was previously reported to occur at 1400-1600 m in fields, meadows, and roadsides of Haiti (Urban, 1898-1928).

Materials

• Poisonous to mammals

S. arvensis is very similar to a fellow member of the Lamiaceae family, Lamiumamplexicaule; these can be distinguished by the leaves on the flowering stems, which are stalked in S. arvensis and sessile (attached without a stalk) and kidney-shaped in L. amplexicaule.

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

S. arvensis is reportedly sensitive to herbicides and nitrogen input as well as shade and soils with pH above 6; it is thus not considered difficult to control, and was listed in 100 of the most rapidly declining weed species in the UK (Hurford, 2007).

24/08/2014 Original text by:

Marianne Jennifer Datiles, Department of Botany-Smithsonian NMNH, Washington DC, USA

Pedro Acevedo-Rodríguez, Department of Botany-Smithsonian NMNH, Washington DC, USA