Vicia Orobus

''Vicia orobus'' is a species of leguminous plant in the genus '' Vicia'', known as wood bitter-vetch. It is found in Atlantic areas of Europe, especially in the rocky edges of seasonally-grazed fields. It grows up to tall, and has no tendrils at the ends of its pinnate leaves. Its flowers are white with purple veins, and are borne in groups of 6 or more.

Description

''Vicia orobus'' is a perennial plant, growing up to tall. Its leaves are paripinnate, with 6–15 pairs of leaflets on each leaf. The flowers are borne in groups of 6–20. Each individual flower is long, and is white with purple veins. The fruit is a 4–5-seeded pod around long.

''V. orobus'' can be distinguished from other species of ''Vicia'' occurring in the British Isles by a number of characters. It is one of three species to lack tendrils (the others being '' V. lathyroides'' and '' V. faba''), with the leaves terminating instead in a short point. It differs from the other two species without tendrils in being perennial, having more than 6 flowers in each inflorescence, having peduncles more than long, and having more than 5 pairs of leaflets in each pinnate leaf. The lack of tendrils is thought to represent a primitive state within the genus ''Vicia''.

Distribution

''Vicia orobus'' has an Atlantic distribution, occurring from northern Spain to Norway, at altitudes of . In Great Britain, ''V. orobus'' has a westerly distribution, and is extinct in South East England. Much of the global population is found in the British Isles, where it is largely restricted to altitudes of , except in the far north (north of Lochinver), where it can be found down to sea level. Its stronghold is in central and north-western Wales.

In Ireland, ''V. orobus'' is declining in numbers, and has been found recently at fewer than a dozen sites, most of which hold very small populations. It is therefore accorded legal protection in the Republic of Ireland, under the ''Flora (Protection) Order 1999''.

In continental Europe, ''V. orobus'' is replaced to the east by '' V. cassubica'', with the division between the two species running through central France. It is present as a native species in Switzerland, where it is the only truly Atlantic species.

Habitat

''Vicia orobus'' is found in a variety of sites, including the edges of woods, on heaths, in meadows or in rocky places over limestone. In Great Britain, it is frequently found at the edges of fields where sheep are grazed in winter, but a hay crop is grown in summer. It is threatened by both overgrazing and undergrazing, as well as other activities, such as grassland improvement and land reclamation. ''V. orobus'' flowers from May to July and is pollinated by bees.

Many species are associated with ''V. orobus'' in Great Britain, including '' Alchemilla glabra'', '' Carex pallescens'', '' Genista anglica'', '' Pseudorchis albida'', '' Rhinanthus minor'', '' Stachys officinalis'' and ''Viola lutea''. At some sites in Ireland, ''V. orobus'' is associated with species such as '' Dryas octopetala'', '' Sesleria albicans'' and '' Geranium sanguineum'', which are characteristic of the flora of the Burren, although ''V. orobus'' does not occur in the Burren, or in floristically similar regions nearby.

Taxonomy

''Vicia orobus'' was first described by Augustin Pyramus de Candolle in the 1815 work '. It is classified in the section ''Vicia'' sect. ''Cassubicae'', alongside species such as '' V. cassubica'', '' V. megalotropis'' and its likely sister species, '' V. sparsiflora''.

References

External links

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{{Taxonbar, from=Q159825

orobus
Flora of Europe
Plants described in 1815