by Richard Bland
St Vincent’s Rocks, the cliff face below the Observatory, is one of the most famous botanical sites in the whole British Isles. It has been visited by every eminent botanist in Britain since William Turner, Dean of Wells, whose Herbal was published in 1551. The reason is that the cliff faces, and the close-cropped limestone turf on the plateau, provide a perfect habitat for a whole range of limestone species, some of which occur nowhere else in the world, and others scarcely anywhere else in Britain.
Two closely related Whitebeams, Bristol Whitebeam and Willmott’s Whitebeam, grow in the Gorge and nowhere else. However recent research using DNA analysis has shown that there are at least 20 microspecies within the confines of the Gorge, many of them unique. The Bristol Rockcress and Bristol Onion grow nowhere else in Britain, and Spiked Speedwell, Rock Stonecrop, Bloody Cranesbill, Pale St John’s Wort, Spring Cinquefoil and Dropwort are all nationally rare or uncommon. Most of these can be found readily growing close to public paths, and some are featured in a showbed on the edge of the Suspension Bridge. These, and a variety of less dramatic rarities, are closely monitored. Much of the maintenance work which keeps the cliffs clear of brambles, cotoneaster and litter is designed to ensure their survival.
The cliffs also offer a series of spectacles as different species come into flower. In early spring they turn yellow as the native Perennial Wallflowers come into bloom. Shortly after a lovely alien allium, Allium roseum, turns them pink, before Ox-eye Daisy changes the colour scheme to white. In winter they turn green as the Southern Polypody, a native fern which has been there all the time, abruptly becomes dominant.
There is a variety of other delights. Parsley grows wild and flowers in late June, just before Fennel. A marvellous limestone thistle, the Dwarf Thistle, whose flowers have no stem and hence are below the reach of the mowers, survive in some parts of the Downs. Harebells appear in July, as does Great Knapweed in a strange white form rather unlike its normal purple.
Alexanders is an umbellifer with dark green leaves which flowers in early spring, but is rarely found more than a mile from the sea and is thought to have been a mediaeval vegetable. Ivy Broomrape grows everywhere in May, even on Clifton walls. It is parasitic on Ivy, but is largely unknown in the rest of the country. Lactuca virosa, the Great Lettuce, a giant plant more than two metres high with fierce spines on the back of its leaves, has invaded in the past decade and spread widely. Green Alkanet is a common weed, yet elsewhere in Britain is scarce.
Another of the joys of Clifton are the plants that grow in the walls. Many flower almost the whole year round. They include Red Valerian, which can be white or purple, Yellow Fumitory, and two blue alien Bellflowers, Adria Bellflower and Spreading Bellflower. They are very similar, and have spread from gardens across Britain, but are particularly spectacular in Bristol. Almost every wall has Ivy-leaved Toadflax. Some walls are clothed in Tutsan, a shrubby St John’s Wort, others in Pellitory of the Wall. Most walls have Harts Tongue Fern, Wall Rue, Rustbyback or Maidenhair Spleenwort growing somewhere. These species are almost totally confined to walls. Wallflowers and Snapdragon grow wild on a few walls, and Lavender has often escaped from gardens on to them. On the tops of walls there is Wall Lettuce, often one of a variety of Cotoneasters, and often Aster, Canadian Fleabane, Blue Fleabane, Leycesteria, Mexican Daisy, garden Alison, Nipplewort and Oxford Ragwort.
Gutters and pavements are other habitats that provide endless fascination. Of course, the authorities try to keep gutters clear, by both sweeping and spreading weed-killer, but if conditions are right, which means warm and damp in April and May, the seeds that lie everywhere just awaiting their chance burst into life. As there is no other competition almost any plant of any species can be found. Many are garden species that have hopped over the wall, some are trees and shrubs spread by birds, some appear abruptly from nowhere, flower, seed and vanish never to be seen again. The lack of competition, a rare event in the plant world, is the key to the extraordinary variety of species that may be found with a little luck. Some are species that are exceptionally rare in the rest of the region.
Clifton is also famous for its botanists. Edward Swete, lecturer on Botany at the Bristol medical school, published his Flora Bristoliensis in 1854, describing the 810 species to be found within ten miles of the Bristol Exchange in Corn Street. Professer Albert Leipner founded the Bristol Naturalists’ Society in 1862 and created the first Bristol University Botanic Garden on what is now University Road. James W White, who ran a chemist’s shop at the corner of Royal York Crescent, produced the finest county flora of its generation in 1912, listing some 1200 species effectively within the bounds of the former county of Avon. His flora is still a key source of information.