Lycopus europaeus L., Gypsywort

Account Summary

Growth form and preferred habitats

This erect, odourless, 60-90 cm tall perennial has a slender, creeping rhizome that gives off runners. Stems are erect, unbranched or sparsely branched, acutely 4-angled, glabrous or very slightly hairy. Very occasionally, large, multi-branched plants can develop under optimal growing conditions. The opposite leaves, 3-10 × 1-4 cm, are shortly stalked, narrowly lanceolate to ovate in outline, with margins coarsely toothed to pinnately lobed near the base of the plant. The leaf shape and deeply toothed margin give the plant a quite nettle-like appearance (Urtica dioica) at first glance.

L. europaeus is a lowland plant found in a wide range of wetland sites including the banks of rivers, canals and ditches, pond and lake margins, tall-herb marshes, fens, swamps, wet fields and open, boggy places in fen-carr woods on moderately fertile, neutral to calcareous, muddy, mineral or peaty organic soils. It does best in half-shade or sunny, sheltered conditions, but is sensitive to trampling and grazing. Gypsywort tolerates temporary flooding and is an early colonist of nutrient-rich, exposed mud and shallow, standing or slow flowing water in newly created or recently disturbed wetlands (Sinker et al. 1985).While it frequently fulfils this colonist role, Gypsywort is also found persisting in established vegetation and then competing with or tolerating pressure from sedges and other much taller and more vigorous wetland species, eg in reedswamp, fen or shaded fen carr.

L. europaeus is so frequent and characteristic a species of wet ground or shallow water habitats that one could argue it should be regarded as a member of our aquatic flora, rather than a purely emergent terrestrial species (Cook 1998).

It also occurs in coastal situations at the top of beaches and in the wetter, slack areas of sand dunes (K. Walker, in: Preston et al. 2002). It is said to be quite salt-tolerant and can grow well in tidal brackish marshes (Chater 2010).

The established strategy of L. europaeus is categorised as C/CR, ie intermediate between a competitor and a competitive ruderal species (Grime et al. 1988, 2007).

Fermanagh occurrence

Very decidedly a species of nutrient-rich, lowland marshy wet ground and, as the tetrad map shows, L. europaeus is almost omnipresent around both Upper and Lower Lough Erne, but it is only occasional in wet ground on other lakeshores and riverbanks in the VC. Gypsywort has been recorded in 112 tetrads, 21.2% of those in the county, but it is very unevenly distributed.

Flowering reproduction

L. europaeus produces dense whorls of tiny, mint-like flowers in the axils of the upper leaves from June to September. Flowers are both larger hermaphrodite (bisexual) and smaller female on the same plant (ie the plant is gynomonoecious). The number of flowers in a whorl can vary from 4-50 or more; the individual flowers are small and sessile. The cup-shaped calyx has a series of spiny projections giving the flower clusters a bristly appearance. The tubular corolla is white, with a faintly bluish tint and purple spots, and is scarcely longer than the calyx lobes. The anterior petal is dotted with a red nectar guide and the corolla throat is densely hairy, protecting the nectar from rain and small crawling insects. There are just two functioning stamens, rather than four and they are exerted beyond the petals (Hutchinson 1972). Pollination is carried out by various small insects, including those with a short tongue (proboscis), since the corolla tube is short and wide (Hutchinson 1972; Garrard & Streeter 1983). The four fruit nutlets, 1.8-2.0 mm, are supported on a large nectar-secreting disk (Melderis & Bangerter 1955). They are 4-sided, truncate at their apex and have thickened corky margins that give them buoyancy in water, enabling water dispersal.

Seed dispersal

After release from the plant, the nutlets can stay afloat for 12-15 months and are readily dispersed, especially along rivers and streams, where the species is frequently found growing, even in crevices in waterside brick walls. Birds, including pigeons also feed on the seed and L. europaeus seed has been recovered from the crop of one that was shot. This does not prove that the nutlets can survive passage through the bird and subsequently grow, but it holds out that possibility (Ridley 1930; Hutchinson 1972; Sell & Murrell 2009). L. europaeus growing around isolated ponds that were fenced off from stock animals does also suggest bird-transported seed as the most likely source (Ridley 1930, p. 547).

The survey of soil seed banks in NW Europe contained three estimates of L. europaeus seed longevity, two of which were transient (less than one year), while the third was 'present', but unassigned to any of the three types; transient, short-term persistent or long-term persistent (Thompson et al. 1997).

Vegetative reproduction

The species has a slender creeping underground rhizome that gives off runners, so it must be capable of some degree of lateral vegetative spread and possibly clonal stand formation. However, the current author (RSF) has not been able to detect any literature mentioning this possibility.

Irish occurrence

Apart from Lough Erne, the other major stronghold of this species in Northern Ireland is undoubtedly Lough Neagh, where Harron (Flora of Lough Neagh) described it as, "very frequent and locally abundant". Elsewhere in Ireland, it is scarce, thinly and widely scattered, and decidedly local (An Irish Flora 1977; New Atlas).

British occurrence

A common wetland species, it has more of a southern and western distribution in Britain in both England and Wales, but becoming increasingly scarce, scattered and coastal northeast of a line between Lancaster and Hull and in the Channel Isles. Overall, it appears stable in both B & I (New Atlas). While the species may have lost populations in some sites due to drainage

and clearance of water courses, it has probably compensated for this by colonising ponds in quarry pits and in other newly created artificial wetlands.

European and world occurrence

In Europe, L. europaeus is widespread and is found in Fennoscandia to 64°N. It also occurs in NW Africa and N & C Asia. The species belongs to the Eurosiberian temperate phytogeographical element and is also a naturalised introduction in eastern N America, together with Australia and New Zealand (Hultén & Fries 1986, Map 1613; Sell & Murrell 2009).

Uses

The plant produces a useful black dye which is fast and permanent for linen, wool and silk (Grieve 1931). Ever since the notion was first propounded by Lyte (1578) in his English translation of the Dutch herbal by Dodens (1554), it was commonly believed that gypsies used the dye produced by L. europaeus to give their faces a darker, more swarthy appearance. However this has been dismissed for many years as mere racial and class prejudice (Grieve 1931; Grigson 1955, 1987).

The fresh or dried flowering herb is described as astringent, hypoglycaemic, mildly narcotic and mildly sedative (Grieve 1931). Extracts inhibit iodine conversion in the thyroid gland and are used in the treatment of hyperthyroidism and related disorders (Launert 1981). It is also reputed to slow and strengthen heart contractions (Brown 1995). The plant has been used in the treatment of coughs, bleeding from the lungs, consumption and excessive menstruation. The leaves have been applied as a poultice to cleanse foul wounds (Chopra et al. 1986). The plant is harvested as flowering begins and can be used fresh or dried, either as an infusion or a tincture. Current uses are predominantly for treating increased activity of the thyroid gland and for premenstrual syndrome symptoms such as breast pain (Karalliedde & Gawarammana 2008) (Plants for a future, pfaf.org webpage for Lycopus europaeus, accessed 4 May 2020).

Names

The genus name 'Lycopus' is a combination of the Greek 'lycos', 'wolf' and 'pous', 'a foot', meaning 'wolf's foot', a translation that suggests little or nothing in relation to the plant and its properties (Gilbert-Carter 1964). There is a fanciful suggestion, however, that it somehow refers to the shape of the rhizome (Hyam & Pankhurst 1995). The Latin specific epithet 'europaeus' simply translates as 'European'.

There is a range of English common names including 'Gypsywort', 'Green Archangel', 'Marsh Hoarhound', 'Water Hoarhound', 'European Bugleweed', 'European Water Horehound' and 'Egyptian's Herb'. The 'Egyptians' were another group like the gypsies who were imagined to use the plant to dye their skin colour (Grieve 1931). 'Hoarhound' is a bit of a mystery as there is nothing white or hoary about the plant, it not even being particularly hairy. The root 'har' means 'hoar', 'grey' or 'pubescent' (Grigson 1974) and the current author (RSF) believes this simply does not fit the plant either.

Threats

None.

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