In last week’s article the sea birds at St Abbs Head were the main subject, and, important as they are, they are only a part of the fascinating selection of wildlife that finds a home and refuge at the Head.
The bedrock at St Abbs Head is very close to the surface over much of the reserve and the thin layer of soil is stony and dries out quickly, especially on the exposed slopes. A host of special small plants thrive in this harsh habitat, they cannot compete with large rank plants found on richer, moist soils.
Found at several sites along the Berwickshire coast, the Rock Rose is abundant on the Kirk Hill where for 40 years the sheep grazing has been managed for the advantage of this plant, with enough grazing to keep large plants under control without overgrazing the Rock Rose, although at the moment a plague of rabbits seem intent on undermining the hillside with their burrows.
The Rock Rose is not a true Rose but is a species of Helianthemum. It is a small sub-shrub growing only a few inches tall with evergreen leaves and bright yellow flowers. The Rock Rose is the host plant for the local and rather special Northern Brown Argus butterfly which is quite a small species. The upper side of its wings are dark brown with orange spots along the margin and a white spot in the centre of the wing. Its caterpillars eat the leaves of the Rock Rose but its numbers are small and do no damage to the plant.
Another special plant found in the short turf, often near the cliff edge, is Purple Milk-vetch (see photo), a small member of the pea family with rich purple flowers. It is found along much of the Berwickshire coast but the number of specimens at many sites is tiny whereas at St Abbs it is reasonably plentiful.
On the north facing cliffs near the lighthouse there is a large colony of Roseroot which is a type of Sedum. It is widespread on cliffs near the top of many of the mountains in the Highlands but here at St Abbs it is quite at home on the sea cliffs.
It is also not related to roses but it is said that its fleshy roots are rose scented if broken. It has yellowish flowers in early summer and the fleshy leaves often take on nice shades of yellow and red in the autumn.
Two other plants which grow in great abundance are the white flowered Sea Campion which has glaucous grey leaves and showy white flowers and of course the Thrift or Sea Pink which grows in great abundance and turns much of the Head pink when it is in flower and is a sight which is almost as amazing as the cliffs of sea birds.