• Order: Lamiaceae - Mint Family
• Genus: Glechoma
• Species: hederacea
• Common names: Ground Ivy, Creeping Charlie, and Gill-over-the-Ground
• Previously named: Nepeta hederacea

• Perennial
• Gynodioecious
• Reproduces by creeping stems and seed
• Native of Europe
• Introduced to America during colonization
• Often found in shaded and moist locations

Description (Stubbendieck et al. 1995 and Hutchings and Price 1999)

• 15-30 inches long
• Prostrate with erect flowering branches
• Roots at nodes
• Four sided stem

• 0.5 to 1.5 inches in diameter
• Almost round or kidney shaped
• Opposite and palmately veined
• Bright green surface
• Has a weak minty odor

• Light blue to bluish-purple corolla (9-18 mm long)
• Calyx tubular (4-7 mm) and pubescent
• Four stamens in corolla tube
• Borne in small clusters in the axils of the leaves

• Smooth and dark brown
• Occur in groups of four
• 1.5 - 2 mm long by 1 mm wide
• Whitish scar at base
• Average air dry mass is 0.69 mg (n=100)

• Fine and fibrous
• Adventitious
• Can develop at the nodes although under natural conditions as few as 50% of nodes may root

Ground ivy occurs throughout Europe, except in Iceland and Turkey. It is also found in Western and Northern Asia to Japan (Hulten 1971).

Ground ivy has been introduced in America where its range extends southwards from Canada to Georgia, Tennessee, Kansas, and Colorado (Gill 1979).

Ground ivy has been introduced in New Zealand, where it is found in many southern localities in the North Island and in many localities throughout the south island (Webb et al. 1988).

Glechoma hederacea is a species of temperate latitudes (Ellenberg et al. 1991).

Glechoma hederacea is primarily a species of the colline-submontane zones of temperate Europe, with an oceanic to suboceanic distribution (Landolt 1977 and Hutchings and Price 1999).

The altitudinal range of Glechoma hederacea has been given from sea level in England to about 1600 meters in the Alps (Grime et al. 1988 and Hulten 1971).

Glechoma hederacea occurs mainly on damp, heavy, fertile, and calcareous soils. It is most frequent in the pH range from slightly acidic to slightly alkaline (pH 5.5 to 7.5), but can also be found on soils with a pH as low as 4.0 (Fitter 1978 and Hutchings and Price 1999).

Ground ivy does not tolerate strongly acidic soils and it is intolerant of salinity (Landolt 1977).

Glechoma hederacea is typically found in fertile habitats where potential dominant species are restricted in vigor by both shade and disturbance (Grime et al. 1988).

Glechoma hederacea becomes abundant only when there is a good phosphate and nitrate supply and a moderately rich supply of cations including Ca⁺² in the soil substrate (Kreutzer and Seibert 1984 and Sinker et al. 1985).

Glechoma hederacea is found in shaded, moist soils of lawns, gardens, wooded hill sides, waste places, pastures, and along streams (Stubbendieck et al. 1995).

Glechoma hederacea is typically a plant of shaded habitats including woodlands and hedgerows. It is frequent on shaded roadsides, in clear-felled and coppiced woodlands, scrub and derelict woodland, and in orchards (Hutchings and Price 1999).

Glechoma hederacea has a limited capacity to persist under tall herbs or beneath continuos tree canopy. It is a species that is most characteristic of lightly or patchily shaded habitats (Grime et al. 1988).

The proportion of biomass allocated to stolons increased from 20% in clones without competition to 36-38% in clones subjected to short and tall grass competition (Hutchings and Price 1993).

Glechoma hederacea is a patch or carpet forming herb. Occasionally it forms extensive monoclonal stands of considerable size, but more often infiltrates, rather than dominates vegetation. It explores habitat by rapid stolon extension and establishes short lived ramets that exploit local resources (Hutchings and Price 1999).

Studies of the effects of leachates of Glechoma hederacea on Raphanus sativus and Bromus tectorum suggest strong allelopathic effects on these species. Leachates from decaying air dried leaves of Glechoma hederacea decreased seed germination, especially in Bromus tectorum (Rice 1986).

When competing with tall grass, Glechoma hederacea increased the length of its vertical petioles bearing leaves. Thus, G. hederacea escaped from competition for light in a vertical direction and responded aggressively to local above ground competition (Price and Hutchings 1996).

 B.) Intraspecific Interactions

Glechoma hederacea has a striking capacity to produce a higher yield under heterogeneous growing conditions than under homogeneous conditions providing the same quantity of resource (Birch and Hutchings 1994).

Glechoma hederacea plants growing in isolation were richly branched with shorter internodes, and thus produced more densely packed ramets (Price and Hutchings 1996).

Glechoma hederacea forms architecturally simple and short-lived ramets which allocate the majority of captured resources to stolon growth and formation of new ramets. Continuos movement through the habitat, and establishment of new ramets in new sites, provides G. hederacea with an effective method for rapidly exploiting resource rich patches in spatially and temporally variable environments, and for escaping from competition, thereby increasing the probability of persistence (Steufer and Hutchings 1994).

Glechoma hederacea petioles are highly variable in length from 10 mm in grassland to over 200 mm in woodland with dense canopy cover and dense ground vegetation (Hutchings and Price 1999).

Clones growing entirely in full sunlight generally produce smaller leaves than clones growing in shade (Sinker et al. 1985 and Grime et al. 1988).

Internodes of the plagiotropic stolons of Glechoma hederacea lengthen under shade and other adverse conditions, including low nutrient supply. This lengthening is accompanied by significant decreases in weight per unit length and stolon cross-sectional area, mainly achieved by reducing the volume of the parenchymatous tissue. The vascular system is considerably less plastic, thus conserving its capacity for resource transport (Price and Hutchings 1992).

Many morphological characteristics are highly plastic, both within stolons and between different stolons of the same clone which experience different growing conditions (Slade and Hutchings 1987).

Germination of Glechoma hederacea is epigeal. Emergence of some seedlings can be observed within 3 days. The radicle emerges first, followed within 1 or 2 days by the cotyledons. The first true leaves begin to expand after approximately one week (Grime et al. 1981 and Hutchings and Price 1999).

Glechoma hederacea overwinters either as small, two leafed ramets, or as 8-10 leafed rosettes produced in the autumn by rooted ramets. From April onwards, the rosettes develop two-leafed nodes at regular intervals along ascending stems. Flowers emerge in the leaf axils between April and July. After flowering the ascending stem continues its vegetative growth (Hutchings and Price 1999).

Individual ramets of Glechoma hederacea behave as annual structures, living for at most one growing season, although the clone itself survives indefinitely, through the production of overwintering daughter ramets. Ramets are normally replaced, in undisturbed natural populations, by vegetative growth of the clone rather than by seeding establishment (Slade and Hutchings 1989).

Gynodioecious species are often insect pollinated, and restrictions in pollen production and dispersal could therefore play a part in determining the fecundity of the females, since they must outcross (Lewis 1941 and Lloyd 1974).

The flowers of Glechoma hederacea are nectariferous. They are insect pollinated, usually by bees (Garrard and Streeter 1983).

The estimated mean pollen dispersal distance was 5.9 meters when calculated on fruit set and 5.3 meters when calculated on seed set (Widen and Widen 1990).

In Glechoma hederacea considerable quantities of resources are allocated to flowering and seed production, as shown by the larger size and longer half-lives of flowering ramets, and the long half-lives of ramets that produce seeds (Slade and Hutchings 1989).

Each flower produces up to four seeds. Flowers are borne in false whorls of 2-5. Thus, there is the potential to produce from eight to twenty seeds per node, but output per node is often well below potential (Widen and Widen 1990).

Stagg found small numbers of seeds of Glechoma hederacea in soil from exarable sites on chalk at several collection dates through the year, with a peak density in August (Stagg 1996 and Hutchings and Price 1999).

Petrov and Palkina found viable seeds of Glechoma hederacea buried in soil beneath a slightly over 40 year old spruce plantation. As Glechoma hederacea would be unlikely to set seed in dense shade, and as the seeds were buried, they had probably been in the soil for 40 years (Petrov and Palkina 1983 and Hutchings and Price 1999).

If females divert their resources to clonal growth instead of seed production, they may gain some advantage over the hermaphrodites and thus escape from extinction (Widen and Widen 1990).

Vegetative spread is rapid, and monocultures covering several square meters are occasionally produced (Hutchings and Price 1999).

The calyx bends down at seed maturation and the seeds are passively dispersed (barochory), although they may further be dispersed by ants (Bouman and Meeuse 1992).

On contact with water, nutlets produce moderate quantities of mucilage (myxocarpy) that fixes them to the substrate (Ryding 1992).

Research indicates that borax can be used to selectively control ground ivy in a cool season turfgrass with only minor and temporary injury to the grass. A late spring application of 610 g/100 m² (20 oz/1000 ft²) liquid Twenty Mule Team Borax provided acceptable and consistent ground ivy control. (Hatterman et al.1996).

Control ground ivy in the spring by raising the runners with a stiff raking and by mowing close to the ground (Schultz 1989).

The best way to control ground ivy in flower and vegetable gardens is by hand pulling and hoeing. The key to effective control of ground ivy in gardens is persistence. Repeatedly pull and hoe the ground ivy until it has been eliminated (Jauron 1997).

Preliminary greenhouse experiments showed that ground ivy was extremely sensitive to borax applications compared with cool-season grasses and other broadleaf weeds that are commonly found in landscapes (Hatterman et al. 1996).

Once the ground ivy has been effectively controlled and a healthy lawn reestablished, the home gardener needs to use good mowing, fertilization, watering, and cultivation practices to maintain a dense, healthy, competitive stand of turfgrass which should help discourage future invasions of this aggressive weed (Jauron 1997).

Super Trimec (2, 4-D + Dicamba + dichlorprop) at 560 ml/100m² controlled ground ivy consistently (>85%) during 1991 and 1992 seasons (Hatterman et al. 1996).

The most effective control comes with the use of combination herbicides that contain the product dicamba. The best time to achieve good control is in the fall, from mid-September to early November. The next best time to control ground ivy is when it is just beginning to flower. This occurs towards the end of April. Two herbicide applications, spaced 10 to 14 days apart are usually necessary to achieve good control (Rindels 1994).

The most effective broadleaf herbicide products on ground ivy are those that contain dicamba. Trimec and Weed-B-Gone Lawn Weed Killer are two widely sold products that contain dicamba (Jauron 1997).

Ground ivy is used by modern herbalists as a remedy for kidney disease, abscesses, tumors, and eye problems (Grieve 1976 and Potterton 1985).

Before the cultivation of hops in the XVI century, ground ivy was the chief source of bitter for flavoring beer (Hyde 1976 and Garrard and Streeter 1983).

Glechoma hederacea ssp. Variegata has been sold as a horticultural plant for use in hanging baskets (Hessayon 1987).

Ground ivy is an aggressive, low-growing, perennial invader of lawns, vegetable gardens, and flower beds (Rindels 1994).

The species is likely to remain widespread and abundant because of its success in exploiting many of the productive and disturbed habitat types that are created by modern land use (Grime et al. 1988 and Hodgson 1989).

• Biology and Habitat
• Control
• Growth and Development
• Interspecific Interactions
• Intraspecific Interactions
• Plasticity
• Reproduction
• Seed
• Variability
• Other

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