British NVC community OV39 (Asplenium trichomanes - Asplenium ruta-muraria community) is one of the open habitat

Vegetation of open habitats in the British National Vegetation Classification system

This article gives an overview of the plant communities formed by vegetation of open habitats in the British National Vegetation Classification system.-Introduction:...

 communities in the British National Vegetation Classification

British National Vegetation Classification

The British National Vegetation Classification or NVC is a system of classifying natural habitat types in Great Britain according to the vegetation they contain....

 system. It is one of six communities of crevice, scree and spoil vegetation.

This community is widely distributed in areas of suitable habitat, especially in the west of Britain.

There are two subcommunities.

Community composition

Four constant species are found in this community:

• Wall-rue (Asplenium ruta-muraria
  Asplenium ruta-muraria
  Asplenium ruta-muraria is a species of fern commonly known as wall-rue. In Germany, it is known as Mauerraute or Mauerstreifenfarn. It is a very small epipetric species, growing exclusively on limestone and other calcareous rocks. It is native to both Europe and eastern North America...
  
  )
• Maidenhair spleenwort (Asplenium trichomanes
  Asplenium trichomanes
  Asplenium trichomanes is a small fern in the spleenwort genus Asplenium. It is a widespread and common species, occurring almost worldwide in a variety of rocky habitats. It is a variable fern with several subspecies.-Description:It grows in tufts from a short rhizome...
  
  )
• Silky wall feather-moss (Homalothecium sericeum)
• Wall scalewort (Porella platyphylla)

Two rare species are associated with the community:

• Hutchinsia (Hornungia petraea)
• Nottingham catchfly (Silene nutans)

Distribution

This community require a lime-rich substrate and its natural habitat is crevices in limestone bedrock, especially in western Britain, where the more humid conditions are favourable to the weathering of suitable rocks. Elsewhere it is also found widely on artificial substrates, such as on buildings and walls built using limestone and on walls dressed with lime mortar.

Subcommunities

There are two subcommunities:

• the Trichostomum crispulum - Tortula intermedia subcommunity
• the Sedum acre - Arenaria serpyllifolia subcommunity

The Trichostomum crispulum - Tortula intermedia subcommunity is dominated by fern

Fern

A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...

s and bryophyte

Bryophyte

Bryophyte is a traditional name used to refer to all embryophytes that do not have true vascular tissue and are therefore called 'non-vascular plants'. Some bryophytes do have specialized tissues for the transport of water; however since these do not contain lignin, they are not considered to be...

s, and flowering plants are scarce.

The Sedum acre - Arenaria serpyllifolia subcommunity typically contains many more vascular plants, with sheep's fescue (Festuca ovina), wild thyme (Thymus praecox

Thymus praecox

Thymus praecox is a species of thyme. A common name is Mother-of-Thyme; "creeping thyme" and "wild thyme" may be used where Thymus serpyllum, normally called thus, is not found. This thyme has a strong scent similar to Oregano. It can be used in cuisine or as an evergreen ground cover for gardens.T...

) and biting stonecrop (Sedum acre

Sedum acre

Sedum acre, commonly known as the Goldmoss Stonecrop, Goldmoss Sedum, Biting Stonecrop, Wallpepper, and the picturesque name Welcome home husband though never so drunk, is a perennial plant native to Europe, but also naturalised in North America. This plant grows as a creeping ground cover, often...

) the most frequent.