Vicia sepium L., Bush Vetch
Account Summary
Native, common and widespread. Eurosiberian boreo-temperate, but widely naturalised.
1881; Stewart, S.A.; Co Fermanagh.
Throughout the year.
Growth form and preferred habitats
Bush Vetch is an extremely common, familiar and widespread, vigorous, tap-rooted, perennial, nitrogen-fixing legume. The dull, pale purple-blue flowers, produced in clusters, are neither as numerous nor as attractive as those of the other common, but less widespread vetch, V. cracca (Tufted Vetch). Aided by its branched tendrils, V. sepium climbs and clambers up to 100 cm or more high on supporting species in practically every hedgerow one examines carefully enough. It is also very common climbing or trailing and decumbent in relatively unmanaged, lightly grazed, or infrequently cut rough grassland, eg on woodland and scrub margins, moist to dry waysides, roadside verges and waste ground. It is less frequently found in tall-herb vegetation on lakeshores and river banks and in almost inaccessible, ungrazed areas on cliffs and steep screes, particularly in limestone areas of the country.
Bush Vetch appears to grow most luxuriantly and is able to compete well with other tall growing plants on moist, neutral to basic soils of low fertility, especially where the ground is relatively undisturbed, but not completely so, thus restricting the vigour of this quite competitive species. The established strategy of V. sepium is reckoned to be intermediate between competitor and C-S-R, placing it in the same category as V. cracca (Grime et al. 1988). While it tolerates only mild levels of acidity (restricted to soils above pH 4.5), but can cope with low nutrient levels, V. sepium is rare or absent from permanent wetlands (Grime et al. 1988). It particularly avoids very acid bogs and wet, peaty, upland heaths and moors and arable land.
V. sepium forms apparently long-lived patches in suitable growing conditions, but it regularly dies down in the autumn, except in mild coastal areas where it often remains wintergreen.
Variation
The species has been split into two varieties, the widespread type var. sepium and the very much rarer endemic coastal var. hartii Akeroyd which has much shorter, prostrate or decumbent, trailing or weakly ascending stems that usually forms mats or hummocks in sand dunes, but occasionally climbs on Ammophila arenaria (Marram Grass). This variety is confined to widely scattered localities in B & I including the island of Coll in the Hebrides (VC 110), the N coast of Sutherland (VC 108) and Caithness (VC 109) and on the Mullet Peninsula, Co Mayo (H27) and at Kincashla Point, W Donegal (H35) in NW Ireland (Akeroyd 1996). Intermediates are also recorded between the two varieties (Sell & Murrell 2009).
Flowering reproduction
V. sepium flowers from May through to August or even later in milder areas. Indeed, at the coast, it can often still be found in flower in December. The inflorescence is a compact axillary raceme of 2-6 flowers borne on very short or no peduncles. The 12-15 mm corolla is reddish purple, the standard petal marked with dark purple veins. The wing petals are paler or bluish and the keel reddish. The whole flower fades to a dull blue or greenish-blue colour. The flowers offer plentiful pollen and well-concealed nectar and attract heavyweight bees (honey bees and bumblebees) that operate the stylar brush pollen transfer mechanism of cross-pollination (Proctor & Yeo 1973, pp. 200-1).
The legume fruit pod, 20-35 mm long, black and hairless, ripens from July to September or later, splitting explosively to throw out 3-7 relatively large, hard-coated seeds (Grime et al. 1988; Sell & Murrell 2009). There does not appear to be any evidence for long-range seed dispersal or any obvious mechanism to make it possible, Ridley (1930) remaining silent on the topic, although he does allow that V. cracca, in somewhat similar habitats, may be carried in mud on boots or animal feet.
It has been pointed out that as with most native legumes, there is little or no understanding of the mechanism and significance of hard-coat seed dormancy under relatively mild B & I oceanic environmental conditions (Grime et al. 1988). The large seeds of V. sepium appear to be inefficiently dispersed and the species is seldom found colonising new, open artificial habitats. However, it remains such a common and widespread species all across B & I, and there does not appear to be any noticeable change in its distribution between the two BSBI Atlas surveys (D.A. Pearman, in: Preston et al. 2002), that the current author (RSF) cannot agree with Grime et al. (1988) that it is, "probably decreasing". Furthermore, there is definite evidence of spread and naturalisation of V. sepium beyond our shores in Europe and elsewhere across the globe, strongly suggesting widespread dispersal assisted by man through his trading and agricultural activities.
V. sepium has a limited capacity for vegetative spread, but seed production appears to be the dominant form of reproduction (Grime et al. 1988). The possibility of a persistent buried seed bank is uncertain: the survey of NW European soil seed banks listed a total of nine studies of this topic, eight of which reckoned V. sepium seed was transient (ie survived less than one year), while the remaining study suggested it survived burial for at least five years (Thompson et al. 1997).
Fermanagh occurrence
V. sepium is the 50th most frequently recorded vascular plant in Fermanagh and it has sites in 469 tetrads, 88.8% of those in the VC.
British and Irish occurrence
Very common throughout B & I, except on exposed coasts and high ground. Other areas that show up even at the hectad scale of the New Atlas map as being unsuitable for the species are wet ground around the English Wash and in adjacent Lincolnshire (VC53 & 54) and Cambridgeshire (VC 29), which together have the most heavily cultivated arable land in the country.
European and world occurrence
Very widespread throughout most of Europe but becoming more scarce or rare towards the south on the Iberian and Balkan peninsulas, although present throughout Italy and even reaching Sicily and Sardinia. Absent from all the other Mediterranean islands and from N Africa and Macaronesia (Azores, Madeira, the Salvages, the Canaries and the Cape Verdes). To the north of Europe, it is present well within the Arctic Circle in Scandinavia and also very rare and possibly introduced and naturalised in S Iceland and the Faeroes and definitely introduced in S Greenland (Ostenfeld & Gröntved 1934; Böcher et al. 1968; Löve 1983). V. sepium is also considered indigenous in temperate Asia and Kashmir and it has been introduced further east in Japan, S Australia and also in N America (Hultén & Fries 1986, Map 1208; Sell & Murrell 2009).
Threats
None.