Urtica urens L., Small Nettle

Account Summary

Growth form and preferred habitats

Apart from the fact that through being an annual U. urens is easily uprooted, it is not easy to distinguish from the closely related, ubiquitous perennial Urtica dioica (Common Nettle), since both species tend to occur mainly in disturbed sites and both are very distinct 'followers of man'. Small Nettle stings in exactly the same manner and with the same burning effect as U. dioica (Emmelin & Feldberg 1947). The Latin specific epithet 'urens' means 'burning' or 'stinging', something which all true nettles do, even when they are dried and very old on a herbarium sheet (Stearn 1992)! Like U. dioica, U. urens is also considered a nitrophile (ie it has a high demand for nitrogen). U. urens is regarded by farmers as an indicator of soil deficient in lime (Greig-Smith 1948).

Distinguishing characters

Even under optimum growing conditions, Small Nettle only reaches a maximum height of 75 cm. More normally it stands around 60 cm tall and thus is generally a lot smaller in stature than U. dioica. Small Nettle often occurs as isolated plants or in small patches, again unlike the sometimes very extensive colonies of Common Nettle (Greig-Smith 1948).

The shape of the leaf base of basal leaves and the relative length of the leaf stalk against the blade have often been used to make the distinction between the two commonest Urtica species: U. urens leaves are not cordate (ie heart-shaped at the base) like U. dioica, and the blades of the lower leaves tend to be shorter than their stalks.

In his New Flora of the British Isles, Stace (1991, 1997, 2010) uses differences in the relative length of the terminal leaf-tooth and its adjacent laterals to separate the two common nettles found in Britain and Ireland: in U. urens the terminal leaf-tooth is about as long as its adjacent laterals, while in U. dioica the terminal leaf-tooth is longer than the adjacent teeth.

When in flower, U. urens is seen to be monoecious, each inflorescence consisting of many female and a few male flowers, whereas U. dioica, as its name indicates, normally has separate male and female plants (Garrard & Streeter 1983; Webb et al. 1996). However, since U. dioica has been widely introduced to very many countries, gene exchange has taken place with other Urtica species, so that due to increased variation the traditional distinguishing characters mentioned have become unreliable, and they now allow only quantitative differences to be made (Hultén 1971). This applies even to normally very conservative characters, including the reproductive strategy of the species, which has become variable in U. dioica, so that monoecious forms regularly occur.

Fermanagh occurrence

There are records of Small Nettle in just eight widely scattered tetrads in the Fermanagh Flora Database, only five of them with post-1975 records. It appears to frequent cultivated ground and light sandy soils on lakeshores. Apart from the first find listed above, the details of the other eight records are: Kesh, 1947-53, MCM & D; shore of Lough Melvin near Garrison, 1947-53, MCM & D; Hanging Rock NR, 1973-5, J.S. Faulkner, D.L. Kelly & W. McKee; E shore of Cargin Lough, Upper Lough Erne, 19 August 1986, L.W. Austin & A.S. McMullin; shore of Derrydoon peninsula, Upper Lough Erne, 28 August 1986, A.S. McMullin; S shore Mill Lough, Upper Lough Erne, 19 September 1986, A.S. McMullin & A. Farr; lakeshore and garden Gublusk Bay, Lower Lough Erne, 6 June 1987 & 22 September 1997, RHN; burial ground N of Tattynuckle at Tullynakerran, 26 April 2007, RHN.

The fact that Fermanagh records of U. urens are so few and so widely scattered in both time and space, suggests it may well be regularly overlooked or taken for young, or poorly grown U. dioica.

Irish occurrence and status

Elsewhere in N Ireland, U. urens is described as "uncommon on waste ground and by houses" (Hackney et al. 1992), and in Cavan, only two records have ever been noted, dated 1987 and 1995 (Reilly 2001). Clearly the distribution and status of this plant needs further investigation, and not only so in Fermanagh. In the past, U. urens has been recorded in all the Irish vice-counties, and has generally been regarded as introduced in Ireland (Scannell & Synnott 1987).

British occurrence and status

U. urens has also been recorded as frequent in all Great Britain vice-counties, but is more common in the east of the country, where it typically occurs as a weed of broad-leaved crops such as sugar beet and potatoes (Grime et al. 1988; Stace 1997, 2010).

Webb (1985) included U. urens in his list of 41 plants previously considered native in the British Isles, but in his view, probably introduced. The New Atlas editors agree with Webb, and they now recognise it as an 'archaeophyte', ie an ancient (pre-1500 AD) introduction (Preston et al. 2002). Stace (1997) considered U. urens as "probably native", but he has revised his opinion and now recognises it is an archaeophyte (Stace 2010).

European and world occurrence

U. urens is widespread throughout western and central Europe, thinning eastwards into eastern regions. It extends northwards from the Mediterranean to well within the Arctic Circle in Norway, Iceland and Finland (Jalas & Suominen 1976, Map 326). Hultén & Fries (1986) suggest U. urens probably originated and is native in central Europe and the Mediterranean area. They conclude it is so widely introduced that its distribution is now almost worldwide, although the known occurrences in the southern hemisphere are still scattered. It is believed that it was introduced to S Australia with hay from Tasmania as early as 1840 (Kloot 1983). The species is also introduced in New Zealand and is regarded as locally common on both main islands (Webb et al. 1988). With its present distribution, Small Nettle is circumpolar (Hultén & Fries 1986, Map 637).

Common names

Four English common names for this species are listed by Britten & Holland (1886), but none are unique to the plant and they all refer to the burning sting.

Threats

None.

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