Vicia lathyroides L.
Family: Fabaceae

A diminuitive annual species that in Ireland is confined to sand dune grasslands. There is evidence of a recent decline in Northern Ireland and its survival here is threatened.

In brief

• An annual plant of short cropped, sandy coastal grasslands
• In Northern Ireland, found in north-west County Londonderry and south County Down, but formerly more widespread
• An easy species to miss due to its short stature and resemblance to common vetch (Vicia sativa)
• Flowers in May and June
• In decline, rare and Northern Ireland the Irish stronghold
• Sensitive to changes in dune management.

Species description
Vetches belong to the legume family of clovers, beans and peas; a familiar example from the genus is the broad bean (Vicia faba), but all wild species are substantially smaller. Spring vetch is a particularly tiny species, reflected by one of its former scientific names Vicia minima. It is a slender and somewhat hairy plant that has a creeping growth habit and stands no more than a few centimetres high. Its leaves have two to four pairs of leaflets often terminating in simple tendrils, and where the leaves join the stem, there are two small leaf-like appendages (stipules) which are shaped like half an arrowhead. Typically, it has only one or two, small (5 to 7mm), and dingy, lilac to blue, keeled flowers per plant.

Life cycle
This is an annual species, that is, it normally germinates, blooms, sets new seed and then dies in the same year. It flowers comparatively early in May and June. Though the flowers undoubtedly attract some insects, self-pollination is prevalent. By midsummer each flower has formed a miniature pea pod containing 8 to 12 seeds. These relatively large seeds are probably long-lived, but to maintain a healthy population some need to germinate in suitable conditions the following year. With comparatively large seeds and no specialised long-distance dispersal mechanism, the species is presumably poor at colonising new sites.

Similar species
It is easy to confuse this species with dwarf forms of common vetch (Vicia sativa) with which it often grows. Common vetch frequently has a black spot on the stipule, and always has larger (>9mm) and brighter flowers (usually with cream colouration as well as the purple), which are produced until September. If in seed, common vetch can be reliably distinguished by its smooth seed coat as compared with the warty seed coat of spring vetch.

How to see this species
Though it also grows in some inland sites in mainland Britain, in Northern Ireland spring vetch is exclusively a species of dry and sandy coastal dune grassland where the sward height is no more than a few centimetres. Murlough dunes County Down, owned by the National Trust, is probably the easiest place to see the species, and it should be in full flower by the beginning of June.

Current status
Globally this is a widespread species. In mainland Britain it occurs around much of the coast where there is suitable habitat as well as inland, but in Ireland it is confined to the coast and is of restricted occurrence, with contemporary records mainly from the coasts of Dublin and Wicklow, and also from Donegal and Wexford as well as the Northern Irish sites which are the Murlough/Dundrum complex in County Down and the dunes between Portstewart and the Bann river, plus areas around Magilligan and the Umbra in County Londonderry.

Why is this species a priority in Northern Ireland?

• Decline and rare with Northern Ireland being the Irish stronghold

It has not been recorded recently at a significant number of its former sites, such as the Ards/Strangford Lough coasts and around Ballycastle.

Threats/Causes of decline
Its back dune sites are under pressure from amenity pressures. It requires a short sward to be reliably present, so it is sensitive to fluctuations in numbers of grazers, both livestock and rabbits. As an annual, it relies on germination each year and unsuitable conditions for a protracted period may wipe out a population.

Conservation of this species

Current action

• The Bann estuary and Magilligan are both ASSIs, and also SACs
• Implementation of the Northern Ireland Hbitat Action Plan for Coastal Sand Dunes.

Proposed objectives/actions

• Maintain the number of known viable populations of the species
• If refound ensure that the population is maintained.

What you can do
Be aware when walking in suitable habitat anywhere in Northern Ireland, especially in May and early June, that what may appear to be dwarf common vetch (Vicia sativa) could in fact be this species. If this is suspected to be the case, contact the Botany Department of the Ulster Museum or CEDaR, National Museums Northern Ireland, 153 Bangor Road, Cultra, Co. Down, BT18 0EU, Tel: 028 9039 5256 or email CEDaR.info [at] nmni.com.

Further information

Links
Northern Ireland Habitat Action Plan - Coastal Sand Dunes

Information on ASSIs

Literature

Text written by:
Shaun Wolfe-Murphy

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