South Gower Cliffs - Gower - page 82

FIG 41 . Golden samphire, a plant of the spray zone. (David Painter)
Peter R. Douglas-Jones for Figures
Wheresoilhasformedandfilledthecrevicesintherock,grassesandmossessuchastuberouspocket-
moss Fissidens taxifolius and rock pocket-moss F. dubius are able to exist and begin to dominate the
flora, together with a wide range of liverworts, such as Riccia sorocarpa . One species of lichen, however,
Squamarina cartilaginea , is able to compete with these plants and grows out of the crevices and onto the
adjacent surface, but in general this 'terricolous' lichen flora is poorly developed compared to sites else-
where in Britain. The most diverse and interesting assemblages are associated with north-facing habitats.
On apparently bare areas of the rock are pinhole-sized pits, thin light-grey crusts and small black or
yellow fruiting bodies which belong to a large number of endolithic (within stone) lichens that grow just
beneath the rock surface. Not much is known about these specialised organisms and few of the current
topics on lichens even mention them. Studies into the process of rock penetration, however, involving
isolation and growth of the organisms involved and the microscopic examination of rock surfaces, are
slowly producing a better understanding of these fascinating communities. A proper survey of all the
lichens on the cliffs is in fact long overdue, given that elsewhere many coastal lichen communities have
been shown to be nationally important.
Although sea cliffs are a harsh environment for plants it seems that the species found on them, while
not growing under ideal conditions, are able to tolerate a situation that is too severe for plants capable