 In 1859, the Reverent Alexander Irvine recorded the following species of plants on the Pewsey Downs; "Cirsium acaule"; "Carduus nutans"; "Cirsium eriophorum"; "Draba verna"; "Bunium bulbocastanum"; "Spiraea filipendula"; "Medicago sativa"; "Onobrychis sativa"; "Cichorium intybus"; "Campanula glomerata"; "Campanula rotundifolia"; "Asperula cynanchica"; "Polygala vulgaris"; "Saxifraga granulata"; "Anacamptis morio"; "Dactylorhiza maculata"; "Gymnadenia conopsea"; and "Botrychium lunaria".The Pewsey Downs National Nature Reserve is an area of unspoiled chalk downland situated on a steep slope above the Vale of Pewsey.It includes the south-facing slopes of Milk Hill, Walkers Hill and Knap Hill.