This site and its content are under development.

Circaea lutetiana L., Enchanter's-nightshade

Account Summary

Native, common. European temperate, but also in Asia and N America.

1882; Stewart, S.A.; Co Fermanagh.

March to December.

Growth form and preferred habitats

A clonal, potentially patch-forming, rhizomatous, polycarpic, herbaceous perennial with erect 20-60 cm stems, swollen at nodes, ± densely pubescent with some glandular hairs. Leaves 4-10 cm, ovate and truncate or slightly cordate at base, sinuate-toothed or distantly denticulate, sub-glabrous or with margins and underside of veins hairy. Inflorescence without bracts, consisting or about 50 well-spaced, open white flowers with parts in twos (Clapham et al. 1987; Sell & Murrell 2009).

While C. lutetiana is most frequently found in damp, shady woods, scrub and hedges, often near water, it also appears more rarely in shaded areas on screes and cliffs. It appears more or less confined to base-rich, moderately fertile, damp soils, and Grime et al. (1988) reckoned the species is intolerant of acidic conditions below pH 4.5. C. lutetiana is especially successful colonising moist, shaded sites with a relatively high proportion of exposed soil or litter and its established strategy is described as Competitive-Ruderal (Grime et al. 1988, 2007).

Enchanter's-nightshade possesses spreading rhizomes and their rapid growth, even in shaded situations, enables the species to vegetatively colonise moist, relatively productive, somewhat disturbed sites within woodland, such as along tracks and rides, in hedge banks and on shaded riverbanks. Other obvious reasons why the plant may be most prevalent or most obvious in linear sites such as these could be the result of better lighting there than under full woodland canopy and the fact that the fruit is a one or two-seeded burr. From August onwards each year, these burrs adhere to the coats of passing woodland animals, or to the lower parts of clothing including the socks of human traffic (Knight 1960). Isolated populations of C. lutetiana are often found in woods a considerable distance from their nearest neighbours, providing circumstantial evidence of effective fruit dispersal by this means.

Fermanagh occurrence

A common and locally abundant plant of shady, damp places throughout lowland Fermanagh, Enchanter's-nightshade is mainly found in the Lough Erne basin. It is recorded in 173 tetrads, 32.8% of those in the VC. Many authors mention C. lutetiana occurring as a garden weed, perhaps colonising shrubbery or other dark corners from nearby hedges, but as far as RHN and the current author (RSF) know, it is not recorded in any Fermanagh garden.

Flowering and vegetative reproduction

For the truly woodland shade plant that this species is, C. lutetiana flowers rather late in the season, from June through into September. The attractive, pure white flowers each have parts in twos, with two caducous sepals (ie soon shed), two deeply bi-lobed petals, two stamens and one style, that is usually also deeply two-lobed. The flowers are self-compatible but they contain nectar and therefore also attract insect pollinators, mainly small flies (Clapham et al. 1987). The 3-4 mm diameter fruit is pendulous and burr-like, being densely covered with stiff hook-tipped white bristles. Passing animals, including man, pick up the burrs and transport the one or two contained seed (Clapham et al. 1987).

Seed is transient in the soil, persisting less than a year (Thompson et al. 1997). The leafy stem dies down after fruiting, but below ground at the base of each one, 2-6 horizontal, fleshy white rhizomatous, overwintering shoots are produced. Although slender and somewhat brittle, the rhizomes can spread up to 30 cm annually through suitably loose soil or surface litter. When the parental axis dies in winter, the underground shoots are disconnected and the following spring the shoot tips break surface and commence growth as new clonal individuals surrounding the position of their forerunner (Salisbury 1964, p. 348).

Despite its lack of evergreen aerial perennation and being noticeably late in developing spring vernal growth, C. lutetiana manages to persist in woods in competition with typical woodland floor species that display these adaptive advantages. This most likely reflects Enchanter's-nightshade's superior colonising ability, conferred by its vigorous rhizome growth (Grime et al. 1988, 2007; Sell & Murrell 2009).

British and Irish occurrence

Enchanter's-nightshade is widespread and common in suitable shady, lowland habitats throughout Ireland, although less frequent in the far west. In Britain, it is similarly widespread except in upland Scotland and in the more acidic terrain north of the Great Glen (Preston et al. 2002).

European and world occurrence

C. lutetiana belongs to the European temperate biogeographical element and is widespread in most of Europe except the NE. It also stretches eastwards into C Asia and southwards to N Africa (Hultén & Fries 1986, Map 1351; Sell & Murrell 2009).

Threats

None.