Glechoma hederacea L., Ground-ivy

Account Summary

Growth form and preferred habitats

This familiar wayside species is a creeping, stoloniferous, patch- or carpet-forming, wintergreen perennial with distinctive, hairy, opposite, long-stalked, kidney-shaped leaves. It is typically found in a range of lightly shaded habitats in woods, scrub, hedgerows, stream-sides and roadside banks, usually on slightly disturbed, fertile soils where competition from potential dominant species is restricted by sub-optimal growing conditions. G. hederacea has a limited ability to tolerate heavy shade from tall herb vegetation or woodland canopy and is characteristic of more open, lightly- or patchily-shaded marginal conditions, where it itself can become the dominant species, forming extensive clonal carpets (Clapham et al. 1987).

Ground-ivy is most frequent and grows best on damp, heavy soils in the pH range 5.5-7.5, but it can occur on the much more acidic, peaty soils down to around pH 4.0. It is principally a lowland species, but can occur up to about 450 m (Garrard & Streeter 1983; Grime et al. 1988, 2007). While it is never frequent in pastures, G. hederacea contains bitter-tasting toxins and is avoided by stock and other herbivores. It is also toxic to some species of rodents, but is a food plant of many invertebrates (Cooper & Johnson 1997; Hutchings & Price 1999).

The established strategy of G. hederacea is categorised as CR/C-S-R, ie intermediate between Competitive Ruderal and the more general balance of all three strategies, Competitor-Stress-tolerator-Ruderal (Grime et al. 1988, 2007).

Variation

Three varieties are distinguished and named in B & I, although their distribution and ecological differences remain unknown (Sell & Murrell 2009). The common form is var. hederacea which has leaves up to 3.0 × 3.5 cm with few to numerous hairs and a corolla 12-15 mm long. The other two are var. minor Gilib., which has the smallest leaves of the three, up to 1.2 × 1.2 cm, often densely hairy and a corolla 8-10(-15) mm long; and var. grandiflora H. Mart., with large leaves, 4.0 × 4.5 cm with sparse hairs and a corolla 15-20 mm long (Sell & Murrell 2009).

Fermanagh occurrence

G. hederacea has been recorded in 128 tetrads (24.2% of the total) widely scattered throughout the VC. However, having said that, it is much more local than one might predict. It definitely seems to prefer the lowland conditions in the Lough Erne basin and, very surprisingly, there is just one isolated record from the Western Plateau uplands (in the Monawilkin limestone district, where it was found by RHN in 1990). On the other hand, the altitude in Fermanagh, lying mostly below 250 m, is insufficient to provide a limiting factor. Excessive soil acidity is a more likely explanation for the distinctly local Fermanagh distribution of the species, which prefers damp, heavy, fertile and calcareous soils (Hutchings & Price 1999).

Flowering reproduction

G. hederacea flowers early in the year, from March to May. The bi-lipped flowers are borne on erect stems 10-30 cm tall, in false whorls (verticillasters) of two to five blossoms, in the axils of the upper leaves, which are generally tinged purple. The violet flower petals are purple-spotted on the lower lip. The flowers are protandrous, contain nectar, and are pollinated by bumble-bees, honey-bees and beetles. The main period of seed set is in June, although this can continue into July (Hutchings & Price 1999). In flowering early, the species avoids the level of shade provided by full summer leaf canopy, thus achieving light conditions that permit its more successful flowering and better seed set.

Ground Ivy, like Wild Thyme (Thymus polytrichus), is gynodioecious, having both perfect bisexual (ie hermaphrodite) flowers and smaller female flowers, either on the same, or on separate bi- and uni-sexual plants (Price 1991). In a rather odd observation, although bisexual flowers are self-compatible, they were still found to require an insect visit for pollination to occur (Hutchings & Price 1999). Despite the gynodioecy adaptation designed to maximise sexual reproduction, reports suggest that seed set is sometimes low, although many other populations do manage to set large quantities of viable seed. Seed set is especially poor in isolated, large, male-sterile clones, which is not surprising (Hutchings & Price 1999).

When fruit is ripe, the calyx bends down and the seeds (a maximum of four nutlets per flower) are passively dispersed. They may be further dispersed by ants (Bouman & Meeuse 1992).

On the basis of studies of the weed flora of an arable field, Chancellor (1985) suggested seed is sometimes short-lived and, therefore, effective regeneration and spread may, in such circumstances, be primarily vegetative. However, other observations, such as the observed rapid colonisation by G. hederacea of secondary or coppice woodland, suggest it may have a persistent soil seed bank that might survive for 40 or more years (Peterken 1981; Petrov & Palkina 1983; Thompson et al. 1997).

Vegetative reproduction

In situations where G. hederacea manages to avoid deep shade and aggressive competition, it can rapidly develop a single species carpet of growth by means of its numerous far-creeping stolons that regularly root at nodes at intervals of around 8-15 cm. Stolons can reach up to 2 m in length, but they die off in the autumn, leaving the rooted ramets to overwinter as small, 8-leaved rosettes (Hutchings & Price 1999). Seed production and efficient dispersal appears in some situations to be relatively rare, so effective regeneration in these cases must often primarily depend upon vegetative spread. Thus transport of shoot fragments may be more significant than seed in achieving long-distance colonisation in such cases (Chancellor 1985; Grime et al. 1988, 2007).

British and Irish occurrence

The New Atlas hectad map indicates that Ground-ivy is widespread throughout Ireland except in VCs along the W coast. An odd area of absence includes the inland portion of Co Leitrim (H29). In Britain, the distribution of G. hederacea thins markedly towards the Scottish Highlands and N Scotland and it is absent from the Hebrides, Orkney and Shetland (Garrard & Streeter 1983; Clapham et al. 1987; New Atlas).

European and world occurrence

G. hederacea s.l. is widespread as a native almost throughout Europe, W & N Asia to Japan. In N America, it is a naturalised alien introduction and it has also been introduced to SE Asia and New Zealand. The present distribution is discontinuous circumpolar and it is categorised as belonging to the circumpolar boreo-temperate element (Hultén & Fries 1986, Map 1603; Clapham et al. 1987; Sell & Murrell 2009).

Uses

Before the introduction of Hops (Humulus lupulus) in the 16th century, Ground-ivy was the chief source of bitter for flavouring and clearing beer for the early Saxons. This is reflected in the English common names 'Alehoof' and 'Tun-hoof' (Grieve 1931).

G. hederacea has been used in herbal medicine as a diuretic, astringent, tonic and gentle stimulant. It has been regarded as one of the most popular herbal remedies for coughs and nervous headaches, and was also useful in treating kidney diseases, indigestion and consumption. A brew of 'Gill Tea' made from Ground-ivy with added honey was a cooling beverage much used for treating stubborn, long standing coughs and for clearing the blood. Gill Tea was also recommended for weakness of the digestive organs, being stimulating and tonic, and for treating all kidney complaints. A snuff made from the dried leaves was used for treating headaches (Grieve 1931).

Several horticultural varieties with variegated leaves occur that are popular for decorative troughs and hanging baskets.

Names

The genus name 'Glechoma' is from the Greek 'glechon', a name in Dioscorides for a kind of mint, 'Mentha pulegium' (Gilbert-Carter 1964; Hyam & Pankhurst 1995). The Latin specific epithet 'hederacea' means 'resembling Ivy' or 'resembling Hedera', referring to its leaves (Gledhill 1985; Stearn 1992).

There are no less than 37 English local common names listed by Grigson (1955, 1987), many of which refer to the spreading stoloniferous nature of the plant, eg 'Gill-creep-by-the-ground' 'Blue-runner' and 'Robin-run-in-the-hedge'.

'Ground-ivy' is a rather poor name, alluding to the running nature of the plant, although its leaves in no way resemble those of Hedera helix (Common Ivy). However, it is a very old name, translating the 'chamaikissos' of the Ancient Greeks and Romans (Grigson 1955, 1987). There are 29 English common names listed by Vickery (2019), some additional to those of Grigson, again emphasising just how common, widespread and familiar the species is to the wider population.

Threats

None.

• Find out more about the format of the species accounts
• View abbreviations
• View references for all species accounts
• View a gazetteer of all the sites