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Galium saxatile L., Heath Bedstraw

Account Summary

Native, common and widespread. Suboceanic temperate, adventive in N Fennoscandia, rare and probably introduced in Newfoundland.

1881; Stewart, S.A.; Co Fermanagh.

Throughout the year.

Growth form and preferred habitats

A prostrate or low-growing, slow-growing, mat- or patch-forming stoloniferous perennial, with a slender tap-root and numerous, tufted, slender, horizontal, wintergreen, non-flowering branches and decumbent or weakly ascending flowering shoots 8-30 cm tall, 4-angled, glabrous, smooth and branched. The flowering stems bear small, white flowers, 3.5-4.0 mm diameter, in few-flowered cymes forming a panicle (Butcher 1961; Clapham et al. 1987). G. saxatile is readily distinguished by its oblong-lanceolate or obovate leaves in whorls of six to eight, that bear forwardly directed hairs or pricklets on their margins, and have a short, narrow point at their tip (not a long, bristle-like tip, as in G. sterneri (Limestone Bedstraw)) (Garrard & Streeter 1983; Webb et al. 1996; Sell & Murrell 2006).

G. saxatile is a common plant of grass heaths, commons, hill grassland and moorland pastures, and is a useful indicator of infertile, acidic, often leached, dry, stony soils and unimproved grasslands. It is a strict calcifuge species. Heath Bedstraw is sufficiently shade tolerant to be able to occur in more open woods, scrub margins, or under the canopy of older heather or tall grasses. It is also known to occur more locally in neglected, derelict grassland, disused quarry spoil heaps and similar disturbed habitats, especially in upland areas (Grime et al. 1988, 2007; W.R. Meek, in: Preston et al. 2002).

Being as common and widespread as it is in these islands, Heath Bedstraw must be rated as a quite competitive or stress-tolerant herb, since despite its low stature it coexists with taller, vigorous growing plants, especially in closed grazed turf in sheep pastures and, at least in Co Fermanagh, it seldom appears in disturbed ground or bare soil conditions. The established strategy of the species is categorised as S/CSR, ie intermediate between a straightforward Stress-tolerator and a more balanced mixture of all three strategies, Competitor, Stress-tolerator and Ruderal (Grime et al. 1988, 2007).

Vegetative and flowering reproduction

Reproduction is both vegetative, by means of spreading horizontal stems that root, leading to the formation of clonal patches, and by seed. However, unlike other species of similar growth form, G. verum does not readily root and regenerate from detached vegetative fragments, and therefore has no real capacity to reach fresh habitats except by transport of seed (Grime et al. 1988, 2007).

Flowering takes place from May to August, the inflorescence being composed of numerous, few-flowered cymes, forming a cylindrical panicle, usually of less than 50 blossoms. The small, pure white, bisexual flowers, 1.5-2.0 mm diameter, are self-incompatible and are pollinated by small insects, especially flies (Garrard & Streeter 1983).

Seed is shed from August onwards, but some is retained on the dying inflorescence until late autumn (Grime et al. 1988, 2007). However, since the species generally occupies closed turf habitats, seedling recruitment is likely to be a rare event. Experimental studies in relatively undisturbed, mesic grasslands where gaps are small and few in number, showed that unlike other species, recruitment of G. saxatile into artificially created 15 cm2 gaps (simulating the scale of gaps produced by rabbit scrapes or molehills) was from a long-term persistent seed bank, rather than from either recent seed rain or a more transient seed bank (Edwards & Crawley 1999).

Fermanagh occurrence

G. saxatile is common and very widespread in Fermanagh as it is in almost every VC in B & I. It has been recorded in 214 of the tetrads, 40.5% of those in the VC and, as the tetrad map shows, it is widely scattered across the county. Locally, habitats range from grassy heaths to better drained areas on blanket bog, in rocky ground, open woods and scrub, generally on fairly damp, but not permanently wet, acid soils. G. saxatile occurs at all levels from the wooded shores and islands of large lowland lakes, such as Lough Melvin and Lower Lough Erne, right up to the summit ridge of Cuilcagh, the highest point in Fermanagh. It is very much more frequent on the higher ground and particularly so in upland grass, heath and bog areas. At the same time, Heath Bedstraw is almost entirely absent around the over-surveyed damp to wet lowland shores of Upper Lough Erne.

While it is a classic example of a calcifuge species, G. saxatile does occur in limestone areas of Fermanagh, eg above Florencecourt, but always there on heavily leached soils that are acidified and nutrient depleted.

In the Sheffield area of England, Grime et al. (1988, 2007) found G. saxatile was significantly more abundant on unshaded, N-facing grassy slopes which, together with other studies, suggested that summer drought may influence its distribution. Drought is a very rare phenomenon in Fermanagh and this type of limitation has not been observed, except that G. saxatile is more frequent in wetter, upland ground.

British and Irish occurrence

G. saxatile is very common and widespread in suitably acid, infertile terrain across the whole of B & I, although there have been local declines in lowland areas, due to habitat losses through urban development and agricultural improvement (W.R. Meek, in: Preston et al. 2002). It is locally absent or more scattered in C & W parts of Ireland and in SE England, where calcareous rocks and wetter, peaty soils are more prevalent.

European and world occurrence

The species belongs to the Suboceanic temperate element in phytogeographical terms and is mainly found in W and WC Europe, extending eastwards very locally to NW Russia and the C Carpathians. It is entirely absent from the Mediterranean region except in N Spain and S France. It is considered adventive in most parts of S & E Scandinavia and in Newfoundland (Hultén & Fries 1986, Map 1516).

Names

The genus name 'Galium' is a name in Dioscorides derived from the Greek 'gala', 'milk', that was first given to Galium verum, a herb widely used to curdle milk for cheese making (Johnson & Smith 1946; Gilbert-Carter 1964). The Latin specific epithet 'saxatile' is derived from 'saxum', 'rock', and means 'growing on or among rocks', or 'rock-liking' (Gilbert-Carter 1964; Gledhill 1985).

The English common name 'Lady's bedstraw' is sometimes applied to this species, as well as more frequently to G. verum, the 'true Lady's Bedstraw' or 'true Our Lady's Bedstraw' (Britten & Holland 1886).

Threats

None.

References

Grime, J.P., Hodgson, J.G. and Hunt, R. (1988, 2007); Webb,D.A., Parnell,J. and Doogue,D. (1996); Garrard, I. and Streeter, D. (1983); Edwards, G.R. and Crawley, M.J. (1999); Britten & Holland 1886; Johnson & Smith 1946; Gilbert-Carter 1964; Gledhill 1985; Hultén & Fries 1986; Preston et al. 2002; Clapham et al. 1987; Butcher 1961; Sell & Murrell 2006;