Area: 33.7 hectares, 83.3 acres.
A narrow ridge of Greensand with a capping of Clay with Flints holding very interesting associations of plants characteristic of acid soils and uncommon in this part of Dorset.
The lower slopes below the hill fort have swards dominated by sweet vernal-grass Anthoxanthum odoratum and common bent-grass Agrostis capillaris. On the steeper parts, sheep’s fescue Festuca ovina, bristle bent Agrostis curtisii and wavy hair-grass Deschampsia flexuosa are the major constituents of the turf and ling Calluna vulgaris, bell heather Erica cinerea, bilberry Vaccinium myrtillus, heath bedstraw Galium saxatile and wood sage Teucrium scorodonia are scattered. Substantial areas of the slopes are covered by scrub, mainly western gorse Ulex gallii with common gorse Ulex europaeus, bramble Rubus fruticosus agg. and broom Cytisus scoparius, but in the east the slopes of Wears Hill have dense stands of bracken Pteridium aquilinum and abundant bluebell Hyacinthoides non-scriptus.
On low-lying ground immediately south of the castle there are small patches of soft rush Juncus effusus and flote-grass Glyceria fluitans where star sedge Carex echinata, low sedge Carex demissa, carnation-grass Carex panicea and cotton-grass Eriophorum angustifolium also occur.
Abbotsbury Castle supports a lichen flora typical of acid substrates including Coelocaulon aculeatum, Peltigera polydactyla, Rhizocarpon obscuratum and Usnea flammea, some of which are uncommon.