Teucrium scorodonia L., Wood Sage

Account Summary

Growth form and preferred habitats

This pubescent, perennial herb produces erect, simple or occasionally branched, acutely 4-angled stems from a much-branched, creeping underground rhizome. Stems are woody at their base and vary from 10-40 cm and may reach 50 cm when flowering. The ovate, decussate, petiolate, opposite leaves are 2.5-7 cm, with crenate margins and rugose, wrinkled (bullate), sage-like surfaces, dark green above, paler beneath. Aerial shoots die back each autumn, but recognisable dead stems (flowering or otherwise) persist attached to the rhizome for up to two years, enabling the plant to be identified at any season. Flowering takes place June to September, the branching flowering stems taller than the barren vegetative branches. The flowers, 9-10 mm long, are borne in pairs on long, slender, terminal, leafless spikes. The bracts beneath the flowers are very different from the leaves and they are shorter than the flowers. The numerous spikes on side branches make up a loose panicle with the flowers all arranged to one side (Hutchinson 1968; Hutchinson 1972; Sell & Murrell 2009).

Throughout B & I, Wood Sage is a common plant of the less shaded parts of lowland, deciduous woodlands, wood margins, rough grasslands, heaths and fixed sand-dunes. In suitable sites it forms extensive diffuse patches by means of its spreading rhizome. T. scorodonia prefers dry, well-drained, mineral, acid or calcareous soils and grows in sites up to an altitude of around 600 m. It is found on a wide variety of generally infertile substrates varying in soil reaction from pH 3.6-8.2. There is evidence of ecotypic differentiation between populations exploiting acidic (pH 4.0-5.0) and calcareous soils (pH >7.0), and between plants in shaded and unshaded habitats (Hutchinson 1968). While there are local exceptions, generally the species is rather sparse or absent in areas where soils are derived from chalk and harder oolitic limestones, or where raw humus or acid organic peat dominates. Areas where this applies are chiefly in SE England, the Irish Midlands and parts of the far west of Ireland (New Atlas).

In Fermanagh, it has not been recorded from walls, hedgerows, quarries, or from other lightly or moderately disturbed, dry or well-drained habitats with apparently suitable soils, other than on a few steep roadside banks, although elsewhere in B & I it is very often found in these kinds of situations, eg in lightly grazed limestone grassland and in openings in young coniferous plantations (Hutchinson 1968; Grime et al. 1988, 2007).

The established strategy of T. scorodonia is categorised as CS/CSR, intermediate between a stress-tolerant competitor and a general C-S-R, a species with a combination of all three ecological strategies, Competitor, Stress-tolerator and Ruderal (Grime et al. 1988, 2007).

Fermanagh occurrence

Rather surprisingly, considering the variety of soils and extent of limestone terrain in Fermanagh, Wood Sage is scarce in the VC and extremely local, being absent from apparently suitable well-drained, acid mineral to mildly calcareous soils on sloping ground in many parts of the county. The Fermanagh Flora Database contains records from only 19 tetrads (3.6% of those in the VC), just twelve of which have post-1975 records. As the tetrad map indicates it is almost exclusively confined to the area SW of Lough Erne.

Where T. scorodonia does occur, it is associated with the typical species of more open areas of deciduous scrub, woodland margins, limestone pavement or rocky scree as, for example, on or below cliffs at Knockninny, Benaughlin or above Doagh Lough, and on the shallow limestone heath and pavement at Legacurragh above Florencecourt.

In sheltered sites in Fermanagh, T. scorodonia is semi-evergreen and has been confidently identified from March through to December.

Flowering reproduction

Flowers in the genus Teucrium differ from all other B & I Labiates in lacking an upper lip to the corolla. T. scorodonia flowers from June or July through to September; the calyx, 4.5-6.5 mm, is campanulate (bell-shaped), the tube of it gibbous (ie swollen, inflated or pouched) at the base, the upper end 5-lobed, with the upper lobe much broader than the other four, which are small and incurved, making it overall look 2-lobed. The corolla, 10-11 mm, is yellow or yellow-green, softly hairy on the outside, one-lipped, the lip with five lobes and the tip deflexed (ie bent back). The central lobe of the corolla is large and sub-rotund, the lateral lobes small and short (Melderis & Bangerter 1955; Sell & Murrell 2009).

The flowers are protandrous and produce nectar and pollen that attracts bees and other insects. Seed production varies widely, insect cross-pollination being the norm although the species is self-fertile. Experimental selfing gave a marked reduction in seed set, close to 40%. Hutchinson (1968) reckoned annual nutlet production per plant could range from just 400 in deeply shaded conditions where insect visits would be rare, to around 48,000 in favourable conditions. The four nutlets are smooth, dark brown and are mechanically shaken out of the enclosing calyx by wind, most travelling a metre or less, although on calcareous soils ants have been observed carrying them (Hutchinson 1968).

Seed longevity in soil has been surveyed across NW Europe, with a total of eight results communicated: three found it transient (one year or less), two short-term persistent (1-5 years), one long-term persistent (>5 years) and two unassigned (Thompson et al. 1997).

The absence of Wood Sage from many apparently suitable sites in Fermanagh and elsewhere may result from poor levels of seed set, or this plus a general lack of dispersal ability. Additionally, the species perhaps displays an over-reliance on vegetative reproduction, which could well play a role in limiting seed production and possibilities of long-distance dispersal. A case for more detailed study of dispersal ability could obviously be made.

Irish occurrence

T. scorodonia is widespread in Ireland, but largely absent from the Central Plain where bogland is common and, also, from the boglands of the western seaboard (New Atlas). Despite a reputedly widespread calcifuge tendency in B & I, T. scorodonia in W Ireland at least, and especially in the Burren, Co Clare (H9), appears indifferent to the base content of the soil. Rather the plant in Ireland appears instead to demand good drainage and it is therefore absent from both heavy clays and wet peat (Webb & Scannell 1983). As it even more obviously avoids wetlands, the observed scarcity of the species in Fermanagh may reflect the extreme oceanic climatic conditions and the consequent widespread occurrence of water bodies and wet, gleyed or peaty soils throughout the whole year.

On the other hand T. scorodonia does have an Atlantic distribution and it is said to grow best colonising and eventually helping to stabilize steep rocky screes, where its well-developed, deeply penetrating and spreading rhizome allows it to survive and compete on inherently unstable ground. In these situations, the loose layers of rock talus provide a mulching effect, maintaining continuously moist soil conditions, even on warmer, south-facing slopes (Grime et al. 1988, 2007).

British occurrence

T. scorodonia is well distributed throughout Britain except for parts of the E Midlands and East Anglia.

Despite the above general habitat features and growing conditions, Hutchinson (1968) quotes examples of T. scorodonia growing and flowering on the edges of Scottish lochs where its roots are submerged for several months each year. In complete hydrological contrast, the species also appears on some exceedingly dry, steep slopes on the English South Downs where there is little or no substrate other than pure chalk! These very weird exceptions to the general rule suggest the species encompasses wide genetic variation. However, other evidence indicates that there is only limited variation within this species. Alternatively the exceptional range of habitats mentioned indicates that a certain level of genetic divergence has occurred and edaphic and shade-tolerant ecotypes exist in at least some parts of B & I (Hutchinson 1966, 1967).

European and world occurrence

T. scorodonia is described as belonging to the suboceanic southern-temperate phytogeographical element and is endemic to W Europe, including the island of Madeira. The species is widespread in W & S Europe and has spread northwards to S Norway (where it is an alien adventive) and eastwards to W Poland and NW Yugoslavia, where it may or not be native. It is also a rare introduction in N America (Hultén & Fries 1986, Map 1577; Press & Short 1994; Sell & Murrell 2009).

Uses

Grigson (1955, 1987) says 'Wood-' or 'Wild-Sage' was not greatly valued by early botanists although it was known as a diuretic, a wound herb and a herb against broken veins, ulcers, French pox and scurvy. The leaves were picked and used to brew tea to treat rheumatism and, since like other members of the family, it contains a bitter tonic substance, it was used in brewing ales and beers before Hops (Humulus lupulus) were introduced. The plant also contains a volatile oil and tannins (Grieve 1931).

The medicinal action is described by Grieve as diuretic, astringent tonic and emmenagogue (ie a substance that stimulates or increases menstrual flow). The same source indicates it was much used in domestic herbal practice for treating skin affections and diseases of the blood, also in fevers, colds, inflammations, rheumatism, gout and as an emmenagogue. It was also regarded as a first rate appetizer and tonic and useful for cleansing old sores. A snuff was also made from powdered leaves to cure nasal polyps (Grieve 1931). Clearly Wood Sage had its supporters for many years, even if its use has declined to near zero nowadays.

Names

The genus name 'Teucrium' is derived from a name given to an unknown plant by Dioscorides, called after the Greek hero, Teucer, a Trojan prince or first king of Troy, said to have first used one of the species in medicine (Johnson & Smith 1946; Gilbert-Carter 1964; Stearn 1992). The Latin specific epithet 'scorodonia' is derived from the Greek 'skorodon' meaning 'garlic', a reference to the plant's odour when bruised.

Five local English common names are listed by Grigson (1955, 1987), 'Gipsy' Baccy', 'Gipsy's Sage', 'Mountain Sage', 'Wild Sage' and 'Rock Mint'. 'Wood Germander' and 'Garlic Sage' are two additional names offered by Melderis & Bangerter (1955). 'Germander' is derived from the Latin 'chamaedrys' a corruption from the Greek 'chamai' meaning 'on the ground' and 'drus', 'oak', as if 'Speedwell' or any other 'chamaedrys' were a 'dwarf oak', from some resemblance of the leaves (Grigson 1955, 1987). Grieve gives 'Large-leaved Germander' and 'Hind Heal' as two more names. A further pair of names in Britten & Holland (1886) are 'Ambroise', or 'Ambrose', a name connected with its use in brewing. 'Bread-and-Cheese' and 'Hart's-ease' (eaten by sick deer) are supplied by Vickery (2019). Grigson suggests the fact that T. scorodonia, "waves no brilliant colour", meant it tended to be rather 'neglected' when it comes to local names, but the current author (RSF) things otherwise.

Threats

None.

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