Bolshayne Fen is a wetland

Wetland

A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....

 in southeast Devon

Devon

Devon is a large county in southwestern England. The county is sometimes referred to as Devonshire, although the term is rarely used inside the county itself as the county has never been officially "shired", it often indicates a traditional or historical context.The county shares borders with...

, England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

. It has an area of 1.62 hectare

Hectare

The hectare is a metric unit of area defined as 10,000 square metres , and primarily used in the measurement of land. In 1795, when the metric system was introduced, the are was defined as being 100 square metres and the hectare was thus 100 ares or 1/100 km2...

s.

The site was designated as a Site of Special Scientific Interest

Site of Special Scientific Interest

A Site of Special Scientific Interest is a conservation designation denoting a protected area in the United Kingdom. SSSIs are the basic building block of site-based nature conservation legislation and most other legal nature/geological conservation designations in Great Britain are based upon...

 on 25 September 1992.

Site Description

This site contains an unusually large and intact valley fen, supporting rich marsh vegetation of a type known only at two other sites in Devon and which is now nationally scarce. The fen occupies a single field at an altitude of 40 m, through which runs a small stream called Nanny's Water, which is a tributary of the River Coly. Its soils consist of deep waterlogged peaty loam

Loam

Loam is soil composed of sand, silt, and clay in relatively even concentration . Loam soils generally contain more nutrients and humus than sandy soils, have better infiltration and drainage than silty soils, and are easier to till than clay soils...

 above Triassic mudstones, with Cretaceous Greensand on the valley sides above. During winter it periodically floods.

Vegetation

The vegetation is mainly of a mosaic of Yellow Iris Iris pseudacorus, branched bur-reed Sparganium erectum and rushes

Juncaceae

Juncaceae, the rush family, are a monocotyledonous family of flowering plants. There are eight genera and about 400 species. Members of the Juncaceae are slow-growing, rhizomatous, herbaceous plants, and they may superficially resemble grasses. They often grow on infertile soils in a wide range...

 Juncus spp., while Greater Tussock-sedge Carex paniculata is locally dominant. Other conspicuous plants include Meadowsweet

Meadowsweet

Filipendula ulmaria, commonly known as Meadowsweet, is a perennial herb in the family Rosaceae that grows in damp meadows. It is native throughout most of Europe and Western Asia...

 Filipendula ulmaria, Marsh-marigold Caltha palustris, Ragged Robin

Ragged Robin

Lychnis flos-cuculi, commonly called Ragged Robin, is a herbaceous perennial plant in the family Caryophyllaceae. It is species is native to Europe, where it is found along roads and in wet meadows and pastures...

 Lychnis flos-cuculi, Watermint Mentha aquatica and Southern Marsh-orchid

Southern Marsh-orchid

The Southern Marsh Orchid or Leopard Marsh Orchid is acommonly occurring species of European orchid....

 Dactylorhiza praetermissa. Also present are four species which are local in Devon: Wood club-rush Scirpus sylvaticus, Marsh Valerian Valeriana dioica, Fen Bedstraw Galium uliginosum and Common Spike-rush Eleocharis palustris. The stream is bordered for most of its length by Alder

Alder

Alder is the common name of a genus of flowering plants belonging to the birch family . The genus comprises about 30 species of monoecious trees and shrubs, few reaching large size, distributed throughout the North Temperate Zone and in the Americas along the Andes southwards to...

 Alnus glutinosa, with a ground flora dominated by Ramsons

Ramsons

Ramsons — also known as buckrams, wild garlic, broad-leaved garlic, wood garlic, bear leek, and bear's garlic — is a wild relative of chives native to Europe and Asia...

 Allium ursinum.

Other biodiversity interest

Brown trout

Brown trout

The brown trout and the sea trout are fish of the same species....

 Salmo trutta fario and Eel

Eel

Eels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...

 Anguilla anguilla are known to occur in Nanny's Water. The site supports a varied reptile fauna, including Grass Snake

Grass Snake

The grass snake , sometimes called the ringed snake or water snake is a European non-venomous snake. It is often found near water and feeds almost exclusively on amphibians.-Etymology:...

 Natrix natrix and Adder Vipera berus

Vipera berus

Vipera berus, the common European adder or common European viper, is a venomous viper species that is extremely widespread and can be found throughout most of Western Europe and all the way to Far East Asia. Known by a host of common names including Common adder and Common viper, adders have been...

. It also supports a number of bird species including Water Rail

Water Rail

The Water Rail is a bird of the rail family which breeds in well-vegetated wetlands across Europe, Asia and North Africa. Northern and eastern populations are migratory, but this species is a permanent resident in the warmer parts of its breeding range...

, which rarely breeds in Devon but has been recorded during the summer at this site. During the winter Snipe

Common Snipe

The Common Snipe is a small, stocky wader native to the Old World. The breeding habitat is marshes, bogs, tundra and wet meadows throughout northern Europe and northern Asia...

 and Woodcock

Eurasian Woodcock

The Eurasian Woodcock, Scolopax rusticola, is a medium-small wading bird found in temperate and subarctic Eurasia. It has cryptic camouflage to suit its woodland habitat, with reddish-brown upperparts and buff-coloured underparts...

 commonly feed within the fen, and Grey Heron

Grey Heron

The Grey Heron , is a wading bird of the heron family Ardeidae, native throughout temperate Europe and Asia and also parts of Africa. It is resident in the milder south and west, but many birds retreat in winter from the ice in colder regions...

 and Barn Owl

Barn Owl

The Barn Owl is the most widely distributed species of owl, and one of the most widespread of all birds. It is also referred to as Common Barn Owl, to distinguish it from other species in the barn-owl family Tytonidae. These form one of two main lineages of living owls, the other being the typical...

occur.