Area: 156.8 hectares.
Formerly part of Arne SSSI. The site includes some botanically very rich road verges which form part of a complex of verges, mostly within the Arne SSSI.
The special interest of this once outstanding area has been greatly reduced by recent reclamation. However parts of this site remain undamaged and bold heathland and acidic grassland with rich associated flora and fauna. Additionally there is a very interesting fen community and some of the drains retain high botanical and entomological importance.
Remaining small areas of unimproved damp acid grassland on the flat alluvial land of the north and west are floristically very varied. These swards which typically have soft andjointed rushes Juncus effusus and J. articulatus in some abundance, are dominated by species of bent Agrostis spp. and purple moor-grass Molinia caerulea. Other frequent grasses include sweet vernal-grass Anthoxanthum odoratum, crested dogs-tail Cynosurus cristatus, heath grass Danthonia decumbens and quaking grass Briza media. Sedges are similarly varied including Carex panicea, C. nigra, C. demissa, C. echinata and herbs include marsh pennywort Hydrocotyle vulgaris, ragged robin Lychnis flos-cuculi, meadow thistle Cirsium dissectum, devil's-bit Succisa pratensis, bog pimpernel Anagallis tenella, marsh bedstraw Galium palustre, heath spotted orchid Dactylorhiza maculata and water mint Mentha aquatica. A small field in the south east of the site, is the only location in Britain for viper’s grass Scorzonera humilis. This is abundant in a sward dominated by bents and red fescue Festuca rubra, with the very local whorled caraway Carum verticillatum.
Heathland and bog are found over the Bagshot Beds on the south and west edges of this site. Whilst in the extreme south there are small amounts of dry heath dominated by ling Calluna vulgaris with bell heather Erica cinerea and common and western gorse Ulex europaeus and U. gallii, most of the heathland is wet. The very local Dorset heath Erica ciliaris is locally dominant in these areas with purple moor-grass and cross-leaved heath Erica tetralix. Other frequent species include white beak-sedge Rhynchospora alba and the sundews Drosera rotundifolia and D. intermedia. The wettest areas support bog communities with a good range of Sphagnum mosses including quantities of the rare S. pulchrum. The rare slender centaury Cicendia filiformis occurs on a track.
At the edge of the wet heath and bog a fen community has developed on base-rich spring water. This is probably the only location in Dorset for two local plants, saw sedge Cladium mariscus and marsh fern Thelypteris thelypteroides. The local sedge Carex lepidocarpa also occurs in this area. Where the fen grades into bog, black bogrush Schoenus nigricans and southern marsh orchid Dactylorhiza praetermissa are frequent.
The drains of this site vary considerably according to their locality. Those within the heathy areas have a rich acid flora including abundant bog St. Johns’s-wort Hypericum elodes, bog pondweed Potamogeton polygonifolius, floating clubrush Eleogiton fluitans, bulbous rush Juncus bulbosus and bladderworts Utricularia spp. Where partly shaded, the local cyperus sedge Carex pseudocyperus grows with royal fern Osmunda regalis. Other drains on the alluvial soils have quantities of reed Phragmites australis and greater pond sedge Carex riparia with yellow water-lily Nuphar lutea, water plantain Alisma plantago-aquatica, lesser water plantain Baldellia ranunculoides and opposite-leaved pondweed Groenlandia densa. In the north where the drains have a more saline character, sea club-rush Scirpus maritimus and bulrush Schoenoplectus taberna e. montani are frequent. Sallow Salix cinerea and common gorse scrub is frequent along the sides of some of the drains. Woodland, confined to the south of the site is acid in character and dominated by birch Betula spp. and pedunculate oak Quercus robur.
The fauna of this site whilst not extensively studied, appears rich reflecting the diversity of its habitats. Full recent information on the dragonfly fauna is not available but a range of the commoner species are present in good numbers and the wet heathland supports the very local small red damselfly Ceriagrion tenellum. Grasshoppers and crickets are well represented and include the local lesser marsh grasshopper Chorthippus albomarginatus in grassland near to the harbour and bog bush cricket Metrioptera brachyptera in the wet heath. A bog supports a good population of the uncommon large marsh grasshopper Stethophyma grossum; and long-winged conehead Conocephalus discolor, another very local insect has been recorded here.
Small numbers snipe Gallinago gallinago, redshank Tringa totanus and lapwing Vanellus vanellus are present throughout the year and it can additionally support wintering wildfowl and waders. An established territory of the rare Dartford warbler Sylvia undata encompasses some of the heathland.