Scutellaria galericulata L., Skullcap

Account Summary

Growth form and preferred habitats

This wetland perennial possesses a slender, creeping rhizome and produces erect to decumbent 4-sided, leafy stems, 15-50 cm long or tall, that are either glabrous or have scattered eglandular hairs and minute glands. The many-branched stems bear shortly-stalked, opposite leaves that are either cordate (heart-shaped) or rounded at the base and have remotely and shallowly toothed (crenate) margins. Flowers develop from July to September in pairs, solitary in the paired leaf axils and appear on one side of the stem only (Clapham et al. 1987).

S. galericulata is frequently found amongst wet, tussocky grass in hollows, or over-topping plants in lowland marshy soils that are subject to regular fluctuations of the water-table. This includes in lakeside tall herb vegetation of water-meadows, marshes and fens. The soils it most commonly frequents tend to be fertile mud or clay, moderately acid to neutral or calcareous in reaction. Although it is found most frequently in sunny situations, it is often lightly shaded and it sometimes grows in half-shade at the base of willows and other shrubs in fen-carr scrub woodland, behaviour that presumably affords it some concealment from grazing and trampling by sheep and cattle.

When growing in shade and competing, Scullcap can become a decidedly straggly plant of considerable size (Crawley 2005). It really can only tolerate light grazing pressure (Garrard & Streeter 1983; Sinker et al. 1985). The established strategy of S. galericulata is categorised as CR/CSR, meaning it is intermediate between a Competitive Ruderal and a more general balance of all three basic strategies – Competitive, Stress-tolerant and Ruderal (Grime et al. 1988, 2007).

In coastal areas of B & I, S. galericulata proves tolerant of salt and brackish conditions and can therefore be found in moist areas of dune slacks or on the sides of coastal drains. It can also occur on boulder beaches in some parts of Scotland (K. Walker, in: Preston et al. 2002).

Fermanagh occurrence

Skullcap has been frequently recorded in 82 Fermanagh tetrads, 15.5% of those in the VC. Seventy-six tetrads have post-1975 records. While S. galericulata is commonly found around Upper Lough Erne in particular, as shown in the accompanying tetrad map, Skullcap is much more local in its distribution when one leaves the Lough Erne basin. It appears chiefly on the wet to damp, intermittently flooded shores of the larger lakes in Fermanagh and along the banks of the River Finn in the SE of the VC. S. galericulata occurs in rather more acidic peaty mud in many sites around Upper Lough Erne and at Spectacle Lough, for example, higher up on the Western Plateau.

Flowering reproduction

Flowers develop from June to September and are arranged in pairs, although actually each blossom is solitary, but is carried in the axil of two opposite leaves, so they appear one sided on the stem. The plant is made less conspicuous by having only a few of the 10-20 mm dull mauve- or violet-blue flowers out in blossom at any one time. The calyx is bell-shaped below and 2-lipped above. Behind the upper lip of the calyx there is an unusual, broad, flat, scale-like pouch attached. After the flower, which is scentless but produces nectar and pollen, has been visited and pollinated by various long-tongued insects, the corolla drops off and the curious pouch on the back of the calyx then falls forward, closing the top of the tube and protecting the developing fruit. As far as the current author (RSF) is aware, this is a unique feature apparently unnecessary in other members of the Lamiaceae.

The corolla is much larger than the calyx and projects well beyond it. While displaying a shade of blue outside, the corolla tube is white inside, the upper lip concealing the stamens and the lower lip beautifully mottled with deep-blue and white nectar guides (Melderis & Bangerter 1955). The four nutlets (single-seeded fruits or achenes) are contained within the dry calyx until they are mature.

When ripe, the wind shaking the stem causes the calyx lobes to separate, permitting the nutlets to be thrown out. They are small, yellow and densely covered with thick processes. Special buoyancy tissue containing air spaces is present in the walls of the nutlets that enables the lightweight propagules to float for up to twelve months and disperse, should they end up in the water around which the parent plant grows (Ridley 1930; Sculthorpe 1967).

The duration of seed survival in soil is probably transient, although there were only two estimates quoted in the soil seed survey of NW Europe and one of them was non-commital (Thompson et al. 1997).

Vegetative reproduction

Since S. galericulata produces slender rhizomes, once established, given sufficiently favourable growing conditions for it to successfully compete, the plant can locally increase and develop clumps or sprawling patches of the species. The relative importance of seed versus vegetative reproduction is not clear, however, and requires further study.

British and Irish occurrence

Well distributed throughout most of lowland Britain, but scarcer in NE England and N & E Scotland. Drainage and development have led to losses of suitable habitat in some parts of England.

In Ireland, S. galericulata has always been scarce and occasional, mainly found inland on lakeshores and along rivers, largely in the Midlands and the north of the island (An Irish Flora 1996; New Atlas).

European and world occurrence

S. galericulata belongs to the Eurosiberian boreo-temperate phytogeographical element and occurs widely and frequently across almost all of Europe and N, W & C Asia. It becomes scarce or absent S of the Pyrenees and the Alps in W Europe and is absent from the more eastern Mediterranean isles. It just manages to reach Algeria in N Africa and is common and widespread across N America, although it is recognised as a separate variety, S. galericulata var. pubescens Benth. Closely related species occur in E Asia, S. yezoensis Kudo and S. ikonnikovii Juz., which taken together help make S. galericulata into a circumpolar distribution pattern (Hultén & Fries 1986, Map 1579; Sell & Murrell 2009).

Uses

Grigson (1955, 1987) refers to S. galericulata as, "another of the bitter labiates" that was used as a 'nervine', ie used to calm the nerves, and as a 'febrifuge', ie an agent used to lower body temperature and give fever relief. The American species S. lateriflora L. (Virginian Skullcap) is more used in herbal medicine than S. galericulata, being regarded as a certain cure for hydrophobia. The plants contain a volatile oil, 'Scutellarin', and a bitter glucoside that yields 'Scutellarein' on hydrolysis.

Skullcap was said to have strong tonic, nervine and antispasmodic action and it was considered slightly astringent. It was used to treat convulsions, hydrophobia, rickets, nervous headaches and severe hiccoughs. It was used to sooth nervous twitches, nervous excitement and for inducing sleep when necessary, without any unpleasant symptoms following (Grieve 1931). It is not recommended nowadays since overdosing can induce ill effects.

Chemists are currently researching the species for medical uses including the creation of drugs for treating cancer.

Names

The genus name 'Scutellaria' is derived from the Latin 'scutella', a diminutive meaning 'a small salver' or ' small dish' or 'saucer', referring to the minute pouch attached to the calyx (Gilbert-Carter 1964; Stearn 1992). The Latin specific epithet 'galericulata' is an adjective formed from 'galericulum', a diminutive of 'galerum', the leather helmet worn by Roman soldiers. It thus means 'helmet-shaped' or 'small capped', like a 'skull-cap', referring again to the calyx that resembles this form of head-dress – and hence the English common name (Johnson & Smith 1946; Gilbert-Carter 1964; Gledhill 1985; Stearn 1992).

Other similarly derived English common names include 'Helmet Flower', 'Hoodwort' and 'Hooded Willow-herb', the latter given as a translation of its old name 'Lysimachia galericulata' by (Gerard 1597) (Britten & Holland 1886; Grieve 1931).

Threats

None.

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