Over 200 species occur in the sward, including Salad Burnet (Sanguisorba minor), Dropwort (Filipendula vulgaris), Fairy Flax (Linum catharticum), Kidney Vetch (Anthyllis vulneraria) and Dwarf Thistle (Cirsium acaule). The rare plants are mainly associated with the small exposures of dolomitic limestone in the southern part of the site. Purn Hill is one of only five British sites for the nationally rare coastal limestone umbellifer species Honewort (Trinia glauca).
The sward contains over 200 plant species, including Salad Burnet, Dropwort, Fairy Flax, Kidney Vetch, and Dwarf Thistle. These plants are mainly found in the southern part of the site, where there are small exposures of dolomitic limestone. Purn Hill is one of only five British locations for Honewort (Trinia glauca), a rare species of coastal limestone umbellifer.