Lathyrus pratensis L., Meadow Vetchling
Account Summary
Native, common and locally abundant. Eurosiberian boreo-temperate, but widely naturalised, including in N & S America and New Zealand.
1881; Stewart, S.A.; Co Fermanagh.
Throughout the year.
Growth form and preferred habitats
L. pratensis is a very variable, conspicuous, yellow-flowered perennial, its tendril-bearing leaves with just one pair of leaflets; it is a vigorous, patch-forming climber of open habitats. These include grassy roadside verges, hedgerow banks and other forms of semi-natural rough unimproved grassland, such as field margins, river banks, cliffs, screes and other similar open, sunny situations. As this clearly indicates, Meadow Vetchling has a very wide ecological amplitude, but like many spreading, rhizomatous species it prefers moist, mesic fertile, moderately acidic, well-lit growing conditions. Despite this, its subterranean rhizome provides energy reserves that allow L. pratensis to tolerate rather drier, less fertile, half-shade, calcareous soils of a wide variety of textures, from clay to sand or even mull humus conditions, although it may not persist for long in such situations.
Despite its relatively high vegetative vigour, L. pratensis is not strongly competitive and can only tolerate light grazing, very occasional mowing, or other mild forms of moderate-level disturbance. Thus it tends to be restricted to sites where the potential dominance of more vigorous species is limited by disturbance. It is seldom if ever found on substrates of pH below 4.5 and it completely avoids waterlogged aquatic situations, wet peat and deep shade (Brunsberg 1977; Grime et al. 1988). When not clambering over other taller-growing, coarse grassy or woody vegetation, L. pratensis is often found entangling and supported by sheep netting wire on fencing. Locally it also appears on lakeshores, cliffs, screes and in limestone pavement.
Flowering reproduction
Flowering takes place from May to August. The inflorescence is an axillary raceme of 5-12 flowers, each with a 10-20 mm, bright yellow corolla, the standard petal with greenish veins. Cross-pollination of the nectar-containing flower is by the stylar brush mechanism involving honey- and bumble-bee visitors (see L. linifolius account for a description). In isolation experiments, less than 4% of flowers managed self-pollination, but clearly the barrier to autogamy is incomplete and self-fertilisation can occur (Brunsberg 1977). Seed is the chief means of L. pratensis dispersal, yet Brunsberg found that in some populations its production was poor, only around 15% of flowers setting any seed at all.
Seed dispersal
The legume pod developed after cross-pollination is between 25-35 mm long, glabrous or finely pubescent, compressed and contains 3-6(-10) rather heavy seeds. Fruit pods ripen from August to October, splitting to release the seed, although as this is without an autochorous dispersal mechanism (ie there is no explosive release), they always fall near the parent plant. The seeds are not adhesive either, so there really is no specialised seed dispersal mechanism of any sort (Brunsberg 1977). After the seed is shed, the aerial shoot dies down in the autumn. Shortly after their release, the seeds quickly develop hard coat dormancy (see the current author's L. linifolius account).
In view of the lack of any obvious or efficient seed dispersal mechanism, the widespread British, Irish and world distribution is rather puzzling. However, man has very probably assisted dispersal in past years, through seed being accidently transported with hay, or eaten along with the plant by animals and transported internally, or spread along with commercial crop seed as an impurity. Plants growing near flowing water might also end up floating to new territory, and seed produced on scree or cliff sites in uplands, might be carried to lower levels by rainwater streamlets.
Seed germination and survival
Seed germination is controlled by the permeability of the seed coat and it is greatest in spring after an overwintering period of dormancy which presumably weakens the seed coat (testa) and allows water and oxygen entry to the embryonic tissues. In cultivation experiments, using seed from all over Europe, only around 10-15% germination was achieved. Accord to Brunsberg (1977), seeds can survive dry herbarium storage and remain viable for up to 90 years. On the other hand, the seed bank survey of NW Europe showed that the great majority of studies concluded that seed was merely transient in soil (ie it germinated or survived less than one year), a small minority of just three studies suggested seed was short-term persistent (ie survived 1-5 years burial) and only a single study found seeds were long-term persistent (ie remained viable for more than five years) (Thompson et al. 1997).
Vegetative reproduction
Under suitable habitat conditions, the creeping rhizome of L. pratensis allows it to spread horizontally and surface root. In Brunsberg's study, "rhizomes up to 7 m long were developed during one vegetative period", presumably meaning one growing season, although to the current author (RSF) this would appear to be quite incredible. However having said this, Brunsberg did find the variation between individuals and populations was very wide in respect to this rhizome capability. Vegetative reproduction is most significant in pastures or meadows where the timing of grazing or cutting prevents seed production and dispersal (Brunsberg 1977; Grime et al. 1988).
Variation
The basic chromosome number in L. pratensis is x=7 and diploid (2n=14) and tetraploid (2n=28) forms have often been recorded, plus a range of other chromosome counts including 21 (triploid) and 42 (hexaploid). In a study of the L. pratensis complex in Europe, Brunsberg (1977) found the diploid form had the widest distribution on the continent, but it was not found in the most western parts, where tetraploids replaced it. Although there was a zone of overlap, the tetraploids appear to be restricted to W & C Europe. Triploids and hexaploids were found only exceptionally. Root tip studies discovered aneusomatic plants with missing or additional chromosomes (generally one missing or extra in diploids, or two chromosomes in the tetraploids) (Brunsberg 1977). The two main cytotypes cannot be distinguished in herbarium material and they have not been given any taxonomic recognition.
Sell & Murrell (2009), in Flora of Great Britain and Ireland 3, recognise three varieties within L. pratensis differing in degree of hairiness and the size of leaflets and legumes: plants of var. pratensis are glabrous or nearly so and have leaflets 12-35 × 4-10 mm and legumes 25-38 mm long; var. velutinus DC. has plants hairy, leaflets 10-25 × 1-5 mm and legumes 30-35 mm long; while var. speciosus (Druce) Druce has plants ± hairy, leaflets 20-40 × 5-7 mm and the mature legume was not seen.
Fermanagh occurrence
In Fermanagh, Meadow Vetchling ranks the 57th most common vascular plant species in terms of record numbers and, with a presence in 431 tetrads, almost 81.6% of the VC total, it ranks 41st in terms of tetrad distribution.
British and Irish occurrence
The New Atlas map shows that Meadow Vetchling is widespread and common throughout the whole of B & I, with the exception of the wet acid boglands of N Scotland and W Ireland. All plants here are tetraploids (Brunsberg 1977).
European and world occurrence
L. pratensis is widespread and considered native in temperate areas of Europe, Asia and parts of N Africa. It is common in almost all of Europe, becoming more scarce southwards and eastwards from the Iberian Peninsula, to Greece, the Caucasus and SE into Iran, Armenia and Turkestan. In the Alps and other European mountain areas, it often grows above the timberline. In N Europe, it is introduced and naturalised in Iceland and Greenland and is considered recently introduced in N Finland, the Faeroes and parts of Norway (Brunsberg 1977). Of the Mediterranean islands, it is present only on Sicily, Corsica and Sardinia. In Asia, it is recorded from Siberia to the Arctic Circle, eastwards to Japan and south to the Himalaya. In Africa, it is present on high ground in Morocco and Ethiopia. L. palustris is also introduced in N America and New Zealand (Hultén & Fries 1986, Map 1216).
Threats
None.