The Isles of Scilly Biodiversity Audit 2008 - Cornwall Wildlife Trust

2.2.1.6 Horsetails, ferns andflowering plantsOverviewThe Isles of Scilly have a rich flora of ferns andflowering plants (which include herbs, shrubs, trees,grasses, sedges and their relatives). Only one speciesof horsetail, Equisetum arvense is found in Scilly, andthat only rarely. Plants are found in a wide range ofhabitats ranging from inland grasslands, wetlandsand coastal habitats to those of very exposed cliffs androcky islets. A number of species found in Scilly haveMediterranean and Lusitanian associations and are atthe northern limit of their distribution. Some speciesof plants are unique to Scilly and others, common insimilar habitats in Cornwall, are absent.Important AreasSome sites in the Isles of Scilly are exceptionallyrich in ferns and flowering plants. These includeheathlands on Wingletang, Salakee and PorthellickDowns, dune grassland, the saline pool on Bryherand the uninhabited islands of Samson, Annet, GreatGanilly and Teän. The coastal habitats are particularlyimportant on all the islands. Inland the wetlands ofHigher and Lower Moors and the lakes on Tresco areall significant plant habitats.Conservation ImportanceShore dock Rumex rupestris is listed on Annex II of theEU Habitats Directive.The presence of shore dock is one of the reasons forSAC designation of the Isles of Scilly. The shore dockappears to be in decline and is now only known fromsites on four islands in Scilly.National BAP priority species are:Chamomile Chamaemelum nobileTubular water-dropwort Oenanthe fistulosa.Shore dock Rumex rupestrisPrickly saltwort Salsola kali kaliShepherd’s needle Scandix pecten-venerisSmall-flowered catchfly Silene gallicaTrends and IssuesHabitat lossAny loss of habitat especially of unimprovedgrassland, wetlands, and coastal habitats has animpact on the biodiversity of the higher plantcommunities. Although the areas may be quite small,in the context of the limited land area on the inhabitedislands, the draining of any wetland or spraying of afew hectares of coastal grassland for example can havea deleterious effect.ManagementLack of management, changes in managementand inappropriate management all have effects onvegetation.Changes in agriculture and horticulture can besignificant on plant communities. For example thedownturn in growing winter-flowering narcissus hasled to the loss of species-rich communities of arableplants (weeds). Many fields formerly used for bulbgrowinghave been put down to grass or alternativearable crops.Abstraction from wetlands and the streams haveresulted in loss of plant species. Higher and LowerMoors are much drier than they used to be. A smallarea of acid bog has disappeared and with it the bogcotton Eriophorum angustifolium and other unusualplants. Cornish moneywort Sibthorpia europaea has alsogone from all but one of its former sites.PollutionUse of fertilisers and herbicides can all be detrimentalto native plant communities.CollectionOne rare fern has been collected in the past. There areat least two fern species in Scilly that may be attractiveto collectors.MonitoringBSBI recorder, Rosemary Parslow monitors the flora ofScilly including most BAP plant species and conductsongoing monitoring projects on the arable speciesand on Ophioglossum taxa. IoSWT monitor shore dockwhen these sites are visited.Species found only in the Isles of Scilly are leastadderstongue fern Ophioglossum lusitanicum, orangebirdsfoot Ornithopus pinnatus, dwarf pansy Violakitabeliana.Species endemic to Scilly and Cornwall includewestern fumitory Fumaria occidentale and Babington’sleek Allium ampeloprasum var babingtonii.Dwarf pansy Viola kitabeliana is endemic to the Isles of Scilly.Photo: Rosemary ParslowIsles of Scilly biodiversity audit Page 18