Vicia sylvatica L., Wood Vetch
Account Summary
Native, rare and declining. Eurosiberian, boreo-temperate.
1882; Corry, T.H.; Ballinamallard.
July and August.
Growth form and preferred habitats
In Britain, at least, this distinctive vetch, like its relatives V. sepium (Bush Vetch) and V. cracca (Tufted Vetch), is usually a trailing, scrambling or climbing, branched, rhizomatous perennial legume, 50-200 cm in height, leaves with 8-20 leaflets and a much-branched terminal leaf tendril. It occupies habitats such as wood and scrub margins, rocky gorges and clearings, various forms of rough wayside grasslands and steep, dry, stony banks. It also grows in open, ungrazed conditions on cliffs, talus slopes and, at the coast, it grows on sea cliffs, lightly vegetated shingle and on screes. In some VCs in B & I, it is regarded as one of the indicator species of ancient woods (Rackham 1980, p. 54). V. sylvatica has always been very much more scarce, occasional and local in Ireland than is the case in Britain, occupying a more restricted habitat range, principally in heathy scrub, on sometimes steep slopes, in coastal situations.
Variation
The species has two varieties, the type var. sylvatica is larger, with weaker, trailing or scrambling stems and leaves with 12-20 leaflets and tendrils 2-7 cm, 2- to 4-branched, the flowering raceme distinctly exceeding the leaves. The alternative form, var. condensata, is smaller with stems 20-50 cm, more rigid, procumbent to decumbent, forming compact patches or low hummocks. It occurs in very scattered, local, coastal sites. Intermediate forms do also occur (Sell & Murrell 2009).
Flowering reproduction
Like the related vetches of the Section Cracca, reproduction is almost entirely by seed. The plant flowers from June to August, the inflorescence being a rather lax, one-sided (secund), raceme of up to 20 flowers, the corolla of each with a beautiful white standard and wing petals, tinged with lilac and striped with purple veins. Pollination is by bees and the resultant legume fruit is 25-30 mm, oblong-lanceolate and acuminate at both ends. When ripe it releases four or five black seeds (Clapham et al. 1987; Sell & Murrell 2009).
Experience of the species in Fermanagh suggests the seed is surprisingly mobile, the plant cropping up at least temporarily and sporadically in several wayside areas within the upland Lough Navar Forest Park. Movement of the plant may well be assisted inadvertently by wheeled transport, or possibly the fruits are eaten and the seeds internally transported by grazing animals. The truth is science does not know how it gets about, but clearly it does.
Fermanagh occurrence
V. sylvatica has been recorded in a total of ten tetrads (1.9%), although only two squares contain post-1975 records. As the tetrad distribution map demonstrates, Wood Vetch has definitely greatly declined in Fermanagh since the 1950s when Meikle and his co-workers recorded it at two completely new sites additional to the seven known from the turn of the 20th century. Their additional sites were: Mullylusty Td, in the Lurgan River Glen, 1947; and on the hill above Drummully Old Church, in the far SE of the VC, 1950. Five of the Victorian stations were discovered by Praeger, who remarked on the fact that Wood Vetch occurred on sandstone on the shore of Lough Fadd and on one of the Lough Navar scarps, but otherwise appeared to favour limestone, eg on the W & E ends of the Cliffs of Poulaphouca (also known as the Cliffs of Magho) (Praeger 1892, 1901c & 1904). The red scarps in the Lough Navar Forest Park are in fact dolomatized sandstone, some of the minerals having been subjected to replacement and hence they are not or only scarcely acidic and are capable of supporting definite calcicoles such as Asplenium viride (Green Spleenwort).
Wood Vetch has only been seen by RHN and the current author (RSF) seven times in Fermanagh in the last 35 years: once at Praeger's Bess Island site, where it was still growing in profusion in the middle of the wooded island, and on four occasions, one or two quite large patches were observed growing in full sun on loose gravel beside forest roads near Shean Lough in the Lough Navar Forest Park. Recently, it has disappeared again at this rather public, presumably vulnerable site; in 2009 and 2010 several patches (up to 10 m x 6 m in size) were found by RHN and HJN growing at the entrance to a quarry in the same forest park.
Irish occurrence
An inspection of the New Atlas hectad map indicates that losses of Wood Vetch in Ireland appear to have occurred in 26 pre-1970 sites, while the number of post-1970 hectads with records totals just 31, the majority of these being in NI.
British occurrence
Today in Britain, V. sylvatica is still thinly but widely scattered across the whole range of latitude, although rather local and with no clear or obvious pattern to its distribution. The one thing definite about its occurrence is that the plant is declining and disappearing from previous stations in numerous areas throughout the whole island, as has been reported from many county floras in recent years. Some of the decline in woodland margins may result from a widespread reduction in coppicing, reducing the light levels the plant requires for its survival (D.A. Pearman, in: Preston et al. 2002). Another suggestion is that the marked decline of the species, measured by the Change in the British Flora survey of 1987-2004, may indicate its vulnerability to increased grazing pressure, and possibly to our rather rapidly changing climate pattern (Braithwaite et al. 2006).
The current author cannot offer any explanation for the decline of the species in Fermanagh, other than the fact that it has always been a rarity and, of course, the smaller and the more isolated any biological population is, the more vulnerable it becomes to a multitude of deleterious factors. A search of published literature shows very little is known of the biology and autecology of the species, which in view of its significant decline in B & I, deserves urgent study.
European and world occurrence
V. sylvatica occurs thinly scattered across N, C & E Europe and W & C Asia as far east as Siberia, but is absent from the Iberian, Italian and Balkan peninsulas, most of France and all of the Mediterranean basin (Hultén & Fries 1986; Map 1203). The latter authors indicate that its occurrence in, for instance, N Europe is not as continuous as they indicate in their published map.
Threats
Apparently none, but the species is definitely in decline and requires monitoring and possibly restoration if it is to survive long-term.