Aegopodium podagraria L., Ground-elder
Account Summary
Introduction, archaeophyte, a common and very widespread, invasive garden escape, locally abundant. Eurosiberian temperate, but naturalised in eastern and central N America.
1881; Stewart, S.A.; Co Fermanagh.
Throughout the year.
Growth form and preferred habitats
This is a notorious rhizomatous perennial garden weed of great vegetative vigour. A. podagraria is easily recognised by its glabrous, 1-2-ternate leaves that resemble the familiar Elder shrub (Sambucus nigra), and hence the English common name 'Ground-elder'. It has stems up to 100 cm, which are hollow and grooved, and the absence of both bracts and bracteoles is very distinctive, as is the possession of its long creeping rhizomes up to 9 mm thick bearing lateral buds (Tutin 1980; Garrard & Streeter 1983; Jonsell & Karlsson 2010). The established strategy of the species is rated CR (Competitive Ruderal) by Grime et al. (1988, 2007) and there is no doubt of the accuracy of the categorization.
Archaeological evidence indicates that Ground-elder was originally introduced and cultivated in Britain during Roman times, around 150 AD, probably both as an edible pot-herb and for medicinal use. The first written record of its presence in Britain dates from 1578 when it was prized as a useful medicinal plant (Ivens 1966). It was not held in high regard for very long, however, since Gerard wrote of it, "Herbe Gerard [one of its many names] groweth of it selfe in gardens without setting or sowing, and is so fruitfull in his increase, that where it hath once taken root, it will hardly be gotten out againe, spoiling and getting every yeere more ground, to the annoying of better herbes." (Gerard 1597, 1633, p. 1001).
A. podograria very readily escapes from cultivation – most likely as small fragments of the very brittle rhizome transported amongst garden waste and also, accidentally, in adhering soil or mud. Under these circumstances it invades and establishes itself very successfully in both native and artificial, disturbed habitats, often in shade or half-shade, near habitation and usually in lowland sites. Soils where the species performs best are moderately damp, nutrient-rich and well supplied with mull humus (Jonsell & Karlsson 2010).
In addition to a range of disturbed artificial habitats including roadside verges, waste- and disturbed-ground, principally near habitation, A. podagraria also occurs widely in woodlands and along shady stream and riverbanks, where it presents a very convincing (however misleading) impression of behaving like a native species, on occasions becoming locally dominant (Clapham 1953; Sinker et al. 1985).
Flowering reproduction
A. podagraria flowers in May and June, the inflorescence being a compound, slightly convex umbel of 10-20 smooth rays and the flowers small, white and slightly irregular (zygomorphic). All the flowers are hermaphrodite (bisexual), but in some peripheral flowers the stamens may drop early (Jonsell & Karlsson 2010). The plant flowers freely and is pollinated by insect visitors attracted by both pollen and nectar. Fruiting takes place in July and August, but seed production is usually poor and seedlings are rarely observed. Sometimes, however, the plant does fruit abundantly and plentiful seedlings can then result. Nevertheless, fresh colonies rarely establish from seed and therefore they do not greatly add to the plant's invasive aggression (Salisbury 1962, p. 499). In any event, the seed is transient, usually surviving in soil for less than one year (Thompson et al. 1997).
Sexual reproduction is, of course, significant in the longer term, maintaining the species adaptive variation and vigour and contributing to the species' dispersal, so that overall the combined reproductive capacity of the species, sexual and asexual or vegetative, is very powerful – despite the plant very often growing in shady wayside sites.
Vegetative reproduction
The most characteristic feature of Ground-elder undoubtedly is its far-reaching rhizome system, the branches of which are white or cream when young and are described as aromatic (Hyam & Pankhurst 1995). From two to five of these underground shoots spread out from the base of each tuft of leafy foliage in all directions, sending up aerial shoots at intervals from nodes that vary in length from just 6 mm to over 10 cm apart, each one supplied with a potential growth bud (Ivens 1966). Experiments have shown that very small rhizome fragments, kept moist in Sphagnum moss, provided they included a node, no less than 84% of them regenerated and developed into flourishing plants. Old rhizome segments were less successful at regenerating, but juvenile segments, even those less than 6 mm in length, developed leaves within a few weeks (Salisbury 1962, p. 499).
The rhizomes of A. podagraria usually remain near the surface, rarely penetrating more than 15 cm deep, but in fertile, moist, not-too-compacted soil, they can spread up to 100 cm horizontally in a single growing season. Even a compacted soil will not stop the spread of the species, however, as many gardeners know! In fact, Ground-elder is often referred to as 'the gardeners' number one enemy', being impossible to extricate from among desirable cultivated plants without resort to repeated application of chemicals (glyphosate) that very much risks the lives of the latter (Salisbury 1962, p. 499).
Not only does A. podagraria invade and tangle with the roots of other plants, it also has a habit of growing under path edges and into the foundations of walls, where digging it out is impossible, and constant re-invasion of cleared areas made inevitable (Ivens 1966).
If it were not for the fact that most of the leaves are basal or radical, which effectively restricts the canopy height of the plant to around 25-30 cm, the species would shade-out more species and dominate far more ground than it currently does (Salisbury 1942, p. 221). As it is, it can form extensive stands, mainly by strong vegetative growth of its rhizomes.
Variation
There is very little variation, although in parts of Denmark, Sweden and Finland an unnamed form exists with once pinnate leaves and oblong to almost orbicular leaflets with an obtuse apex (Jonsell & Karlsson 2010). A variegated cultivar 'Variegatum' has leaves edged and splashed with ivory (Griffiths 1994). As it possesses less chlorophyll, it is not quite as vigorous, competitive and invasive as the normal fully green form.
Fermanagh occurrence
A. podograria has been recorded in 294 Fermanagh tetrads, 55.7% of those in the VC. In cold winters, the plant dies down and goes dormant, but in milder, more sheltered conditions it remains wintergreen. It has been recorded during every month of the year in Fermanagh, but it is certainly more prevalent between March and early November.
British and Irish occurrence
The same story of gradual spread from cultivation applies over almost all of B & I, the only hectads free of the grip of this pernicious weed in the New Atlas map being wetlands, highlands and extremely acidic peatlands, chiefly located in NW Scotland and in W Ireland (Preston et al. 2002).
European and world occurrence
As with other introduced aggressively colonising weeds, it is not easy to identify just where A. podagraria originated, but probably it was in the moist deciduous forests of C Europe (Clapham 1953). Nowadays, it appears native in moist woodland in most of temperate Europe, south to S France and Italy and eastwards to the W Caucasus and W Siberia. However, it has spread with man much wider than this, even to Arctic Scandinavia as well as to temperate N America (Tutin 1980; Hultén & Fries 1986, Map 1395; Jonsell & Karlsson 2010).
Uses
One of the most widely used English common names for A. podagraria is 'Gout-weed', sometimes amended to 'Goatweed'. This name has arisen as the plant has for centuries been recommended by herbalists as a cure for the very painful ailment gout. Indeed, the botanical name 'Aegopodium' is based on the Greek 'aix', 'aigos' meaning 'a goat' and 'pous', 'podos' meaning 'a foot', allegedly referring to the shape of the leaves (Gilbert-Carter 1964). The Latin specific epithet 'podagraria' is also derived from 'podagra' meaning 'gout', or 'good for gout' (Gilbert-Carter 1964).
Gout is a painful form of arthritis that can arise suddenly as an inflammation of the joints due to uric acid crystals accumulating around them. It usually affects people over 50 years of age, especially older men, and it often first appears as a red, swollen and acutely painful big toe. An interesting modern endorsement of the herbal efficacy of the species for treating gout appeared in BSBI News 82: p. 51 (Senior 1999), although the current author (RSF) suggests it might be better to rub an extract of the leaves on the sore joint – rather than to drink it, as Mr Senior reports he did.
The white rhizome is described by Grieve (1931) as, "pungent and aromatic, but the flavour of the leaves is strong and disagreeable". The plant is diuretic and astringent and, "can be successfully employed internally for aches of the joints, gouty and sciatic pains, and externally as a fomentation for inflamed parts." Also, "the roots and leaves boiled together, applied to the hip, and occasionally renewed, have a wonderful effect in some cases of sciatica" (Grieve 1931).
Oddly, A. podagraria gets no mention in the Medicinal plants in folk tradition: an ethnobotany of Britain and Ireland (Allen & Hatfield 2006), which suggests these authors had little or no faith in the use of the species.
In addition to its history in herbal medicine, A. podagraria has also been used as a pot herb for many centuries. The leaves were boiled and used like spinach. They are described by Mabey (1996) as, "making a stringy but tangy dish". The leaves were also eaten as a spring salad (Grieve 1931).
Names
The undesirability of a weed can often be judged by the number of names applied to it by gardeners and others. Grigson (1955, 1987) lists 20 names and Vickery (2019) also manages 20 (not identical to Grigson's list), including 'Farmer's plague' and 'Gardener's plague', plus other names that indicate the ability of the plant to spread rapidly, such as 'Jack jump about' and 'Jump about'. Grieve (1931) gives an additional nine names not mentioned by Grigson and seven absent from Vickery's list. Assessed in this way, A. podagraria must qualify as one of the worst weeds in the world, at least as far as gardeners and farmers are concerned.
At a glance, the leaves are not unlike those of Elder (Sambucus nigra), and hence names such as 'Ground Elder', 'Dog Elder', 'Dwarf Elder', 'Dutch Elder', 'Bishop's Elder', 'Wild Elder' and so on (Grigson 1955, 1987). Many of the names have 'ash' as an element, eg 'Ashweed', but this is associated not with the tree, but rather with 'ache' = parsley. So we have mention of 'Ground Ash', 'Pot-ash', 'White Ash', 'Achweed', 'Wild Esh' and 'Weyl-ash' (Grieve 1931; Grigson 1955, 1987; Vickery 2019).
Threats
A persistent and vigorous ground cover herb, mainly in shady habitats both 'artificial' and more natural, A. podagraria is so common, widespread and thoroughly naturalised, that in suitable vegetation it can look perfectly native.