This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
In addition to inland rocks and rock soils there are the rocks along the coast, forming cliffs of some height, with bare faces and surfaces covered by grass or heath, etc. The proximity of the sea and the regular occurrence of sea breezes, gales, mists, etc, tend to obliterate the effect of the chemical composition of the rocks themselves, and to transform the vegetation into a halophytic type of formation. And the conditions upon the cliff face resemble those of mountain-tops, the sides of the cliffs being often spray-covered and moist; whilst innumerable caverns exist where moisture-loving ferns are especially at home, and, fortunately for their existence, inaccessible.
On such rocks (cf. Section VII) occur many maritime species, as Wild Paeony (Steep Holmes), Welsh Poppy, Wild Cabbage, Woad (Severn estuary), Sea Stock, Tree Mallow, Scurvy Grass*, Sand Spurrey, Pearlwort, Stonecrop, Samphire, Lovage, Golden Samphire, Sea Plantain*, Buckshorn Plantain*, Cotoneaster (Great Orme's Head, now protected), Thrift*, Sea Lavender, etc. It is a noticeable fact that some of these (marked with an asterisk) occur also upon inland rocks at high altitudes, thus showing the influence of a rupestral habitat.