Heswall Dales is regarded as the second best example (after Thurstaston Common) of lowland heath in Merseyside, hosting localised species including Western Gorse Ulex gallii, Many-stalked Spike Rush Eleocharis multicaulis and Green-ribbed Sedge Carex binervis.
paivae occurs in oak woodland and pine woods growing over Ulex, Erica cinerea and Cistus spp.
The calcareous grassland is dominated by Festuca species and Dactylis glomerata, while the scrub towards the west of the site is dominated by Hawthorn (Crataegus monogyna) and Blackthorn (Prunus spinosa), while that to the east consists of Common Gorse (Ulex europaeus) and Bramble (Rubus fruticosus agg).