Vicia sativa subsp. segetalis
(Thuill.) Gaudin, Common Vetch
Account Summary
Introduced, occasional.
May 1978; Northridge, R.H.; Killyvilly, near Enniskillen.
May to September.
Identification
V. sativa subsp. segetalis is distinguished from other annual members of the V. sativa aggregate by its usually bi-coloured, 9-26 mm flowers, the standard petal much paler than the wings and by its numerous narrow, smooth (unconstricted), usually glabrous, brown to black ripe fruit pods 28-70 mm long. The average plant is also an altogether much more robust form of the members of the V. sativa agg. and, unlike subsp. nigra, the leaves are not or only scarcely heterophyllous. V. sativa subsp. sativa, subsp. nigra and subsp. segetalis are not genetically isolated from one another and the complex pattern of variation they encompass is almost certainly the result of extensive inbreeding (Hollings & Stace 1978).
For quite a long period in the 20th century, V. sativa subsp. segetalis was an important, widely sown animal fodder and green manure crop. However, its use in agriculture has more or less ceased as it has been replaced by other legumes in grass seed mixtures (Killick 1975).
Fermanagh occurrence
This subspecies is occasional, widely scattered and sometimes apparently established on various forms of disturbed ground in the Fermanagh lowlands, including in lakeshore grasslands, a sand pit, a disused quarry, roadside verges and urban and rural waste ground. There are records for this previously widely grown fodder and green manure plant from a total of 22 tetrads, 4.2% of those in the VC. Around 75% of the records for the plant were generated during the exhaustive field-by-field study of the shores of Upper Lough Erne made in 1986 by the EHS Habitat Survey Team and this obviously skews the distribution towards this area of the VC as shown in the tetrad map.
Transfer of records
Due to inherent genetic and phenotypic variation associated with habitual inbreeding within the V. sativa species aggregate, hybridisation with closely related taxa and the breeding of large numbers of cultivated strains, some of which have escaped into the wild and crossed with wild forms, there has developed an almost continuous spectrum of variation. This amount of variation, together with differing taxonomic treatments and nomenclature confusion dating right back to Carl Linnaeus, led to this subspecies being erroneously identified as subsp. sativa at the time of the Upper Lough Erne EHS survey (Hollings & Stace 1978; Clement & Foster 1994).
Prior to Stace's New Flora of the BI (1991 and later editions), there was confusion between subsp. sativa, subsp. nigra and the more commonly planted subsp. segetalis. Consequently, RHN & the current author (RSF) have decided, on the balance of probability, to transfer all the supposed subsp. sativa records dating between 1980-91 across to the more widespread, more persistent and very much more likely subsp. segetalis. This is a far from ideal position to be in, but we believe it draws the best picture of the likely Fermanagh situation of these three forms of V. sativa over the post-1975 period of the local recording effort and the creation of the Fermanagh Flora Database.
Lathyrus linifolius (Reichard) Bässler (= L. montanus Bernh.), Bitter-vetch
Native, occasional to locally frequent. European temperate.
1881-2; Barrington, R.M.; Co Fermanagh.
April to January.
Growth form and preferred habitats
This variable perennial legume has a creeping, tuberous rhizome and produces erect, glabrous, branched, winged stems, 15-50 cm tall. The pinnate leaves have 4-8 leaflets, lack a tendril and end in just a short point. Its shallow fibrous mycorrhizal roots also bear nitrogen fixing nodules.
L. linifolius is a scrambling, slow-growing, occasionally loose patch-forming plant of continuously moist to damp, but well-drained, acid to neutral, but always fairly unproductive, nutrient-impoverished soils. Suitable substrates and growing conditions generally occur in rocky or stony, moderately to heavily grazed, heathy meadows and pasture grasslands. In both low-lying and upland situations these habitats can merge into slightly drier, blanket bogland slopes, or occur on the margins of flushes where Calluna vulgaris (Heather) and other heathers tend to come to the fore (Grime et al. 1988; D.A. Pearman, in: Preston et al. 2002).
Alternatively, L. linifolius also grows in light shade in low-growing vegetation on stony, moderately acid heaths – some of which are possibly in the process of degrading to unproductive grassland under various pressures. Additionally, it appears on damp ledges of usually N-facing cliffs, or on the margins or more open areas in scrubby or woodland vegetation, often but not always in fairly exposed situations. In this rather wide range of habitat situations, L. linifolius avoids permanently wet ground, extremes of pH (ie it usually occurs in conditions above pH 4.0 and is rare at pH 7.0). In pastures, it avoids moisture stress, heavy grazing and other forms of excessive disturbance. In terms of its established growth strategy and competitive ability, L. linifolius is considered intermediate between C-S-R and a stress-tolerator (Grime et al. 1988).
In lowland, semi-shaded situations in open deciduous woodland or scrub, Bitter-vetch makes use of its 'semi-vernal' growth and reproductive strategy. Using energy resources stored in its overwintering tuberous rhizome, the plant puts on a growth spurt in early spring producing its aerial stem and leaves. It then flowers as early as April onwards, although in contrast in more upland or full sun conditions of other habitats, this may often be delayed until the end of May. (Grime et al 1988).
Probably on account of its predominantly early season growth, followed by very limited further shoot extension throughout the summer and with the aerial parts then dying down in the autumn, L. linifolius tends to be absent from pastures that are regularly grazed in the spring, or which are heavily grazed, or fertilised and 'improved' at any time of year (Grime et al. 1988).
Flowering reproduction
Flowering begins early in the season in April and continues into July. The inflorescence is an axillary raceme with 2-6 flowers borne on peduncles longer than the leaves. The flower is 10-16 mm long, with pale, bluish-mauve petals, the keel deeper in colour and greenish towards its base. Lathyrus and Vicia flowers share a secondary pollen presentation model similar to that of the genus Campanula in which pollen from the ten stamens is first shed while the flower is still in bud into the folded keel around the tip of the single style which is furnished with a brush of hairs near the up-turned stigma. The pollen ends up either shed onto the stylar brush, or into the tip of the keel, where the brush sweeps it out when the keel petals are depressed by the weight of a visiting honey- or bumble-bee. It takes a powerful insect with a long tongue (proboscis) to reach the nectar at the base of the ovary within the anther filament tube. By the time the flower is open and ready for pollination the stamens have shrunk and retracted, but the stigma brush is fully charged with pollen as it comes into contact with the underside of the bee's abdomen when it hovers or sits astride the keel and reaches into the flower for the well-concealed nectar (Proctor & Yeo 1973).
The flowers are self-incompatible, making cross-pollination essential for seed production. The legume pod is 25-45 mm long, sub-cylindrical and contains 4-10 large seeds. Seeds are released explosively by the rupture of two sutures or lines of weakness as the ripe pod wall dries and suddenly splits, hurling the seeds out. Seed is shed between July and October, but it does not travel far from the parent plant. In common with other legumes, L. linifolius seeds can germinate immediately or soon after release in the autumn, but within days they rather quickly develop hard-coat dormancy. This then requires physical scarification or over-winter weathering before the seed coat weakens and allows water and oxygen to be imbibed, so that subsequent spring germination may occur.
Vegetative reproduction
A balance of seed and vegetative reproduction occurs, but in many instances the latter is possibly the most productive. Effective regeneration is achieved by lateral growth of the creeping tuberous rhizome in the upper layers of soil or under leaf litter on woodland margins or in canopy gaps (Grime et al. 1988).
Variation
There is sufficient genetic and phenotypic variation within L. linifolius for Sell & Murrell (2009) to describe three varieties: var. montanus (Bernh.) Bässler with leaflets 25-50 × 10-25 mm, narrowly elliptical to elliptical, obtuse-mucronate at apex; var. linifolius with leaflets 20-50(-100) × 0.5-3.0(-5.0) mm, long-linear, narrowly acute at apex; and var. varifolius (Martrin-Donos) P.D. Sell with leaflets 18-50 × 3-10 mm, narrowly elliptical, those of the lower leaves usually broader than those of the upper, mostly pointed at the apex.
The distribution and ecology of these three varieties in B & I is not properly understood as yet, although they are all regarded as widespread in continental Europe (Sell & Murrell 2009). Stace (2019) confines himself to remarking that, "our plant is var. montanus."
Fermanagh occurrence
On the more upland areas of Fermanagh limestone terrain, L. linifolius very often grows in association with Calluna vulgaris (Heather) in small pockets of acidic peaty conditions developed on top of heavily leached, generally shallow, 'ranker' soils, or over very shallow rendzina profiles. The current author (RSF) regards Bitter-vetch as a definite calcifuge species and it is occasional to locally quite frequent and widespread in Fermanagh, having been recorded over 200 times in 92 tetrads, 17.4% of those in the VC.
As the tetrad map displays, the Fermanagh presence of Bitter-vetch is scattered throughout most of the VC, but it is heavily weighted towards the Western Plateau, where the upland scarps and the limestones predominate. Agriculture is also less intensive and human population is at its lowest in this region of the county. There is no evidence in the Fermanagh records of any decline in the presence of this legume in the VC, although the record details of early finds in the county are really too sparse and sketchy to display any trend.
British and Irish occurrence
Bitter-vetch is common and widespread throughout most of Ireland, although rarer or absent in much of the intensively managed agricultural Midlands where grassland improvement has been most extensive. It is also absent in the unsuitable wet peatlands of the far west.
In Britain, although there has been a definite decline since the 1950s, L. linifolius is still very widespread, except in SE England and NW Scotland, presumably for similar reasons to the Irish experience (D.A. Pearman, in: Preston et al. 2002). As the narrow range of suitable habitats becomes ever more encroached upon and modified, the decline of L. linifolius appears increasingly likely (Grime et al. 1988, 2007).
European and world occurrence
L. linifolius is widespread in S, W & C Europe reaching north to the Baltic region and E Russia. It becomes scarcer towards the south in the Iberian peninsula and the Balkans, although it is present throughout Italy including the far south. It is absent from all the Mediterranean islands, but has one isolated foothold in NE Africa (Hultén & Fries 1986, Map 1215).
Uses
The tuberous rhizomes were previously collected, dried and stored for famine food and for medicinal use in Scotland, and they were even used to flavour whiskey. Chewing dried rhizome was thought to sweeten the breath after heavy drinking and prevent drunkenness (Garrard & Streeter 1983; Darwin 1996).
Threats
None.