H. nummularium is common in calcareous habitats, while H. oelandicum is scarce in Britain and is restricted mainly to coastal areas, with North Wales being one of its hotspots. On Prestatyn Hillside it seems to favour areas around limestone outcrops, where the soil is thinner and presumably competition is less intense. H. nummularium is found throughout the site including in moderately coarse grassland where it is able to hold its own.
|Helianthemum oelandicum, hoary rockrose|
|Helianthemum nummularium, common rockrose|
The greatest threat to this site (which is designated for an assemblage of rare or scarce plant species) may be from invasive scrub, including several Cotoneaster species. As it is very steep and not fenced grazing presents multiple challenges and is unlikely to be a practical option, so the continuing scrub clearance which is being carried out by hand is probably the only option. Some areas of good habitat, however, would be lost if this scrub clearance (which appears to have been successful in recent years) was not continued.
|Cotoneaster spp. together with native scrub spreading over the hillside|