REPORT ON THE LICHENS OF EPPING FOREST. 93
have already remarked the almost entire absence of fruticulose
forms, such as Evernia, Ramalina, and Usnea, which are
common enough in other districts of the S.E. of England.
In the Forest, perhaps the most abundant tree-dwelling lichen
of all is Lecanora varia, which (with its doubtfully distinct
relative, L. conizaeoides) is universally met with clothing the
trunks and branches of trees ; in open situations, such as about
"Black Bushes," N. of Earls' Path, Loughton, and elsewhere,
the stems and branches of small hawthorn bushes are frequently
entirely covered with this lichen, in full fruit, giving the bushes
a characteristic, hoary grey-green appearance, from which
only the smaller and younger twigs are exempt. These smaller
twigs show, too, that the lichen starts from definite centres,
where spores have germinated, whence, spreading as circular
patches, these at length coalesce and clothe the entire bush
with a dense tomentose fur ; occasionally, another lichen, Par-
melia physodes, form labrosa, grows with Lecanora on the
older branches of the hawthorn. Bushes of Sallow, small Crab
and Oak trees, and the stems of Gorse and heather are so covered,
and the same two species of lichens are often seen associated
together on old Birch trunks, especially the rough, corky portion
near the butt.
On bare trunks of Hornbeam, where free from Chlorococcus,
many of the less conspicuous crustaceous lichens find their
habitat, the more characteristic forms being Lecanora rugosa,
sub-sp. chlarona, Pertusaria wulfenii, Lecidea griffithii (this
species is extremely abundant in a spermogoniferous condition),
Enterographa crassa, Opegraphas and Graphis of various species,
and Acrocordia geminata.
On decaying tree-trunks. Lecidea granulosa sometimes occurs
in great profusion, although its more usual habitat is, as already
stated, on bare heathy ground.
On the cut ends of stumps and on decorticated timber,
Parmelia fuliginosa and Lecidea flexuosa are often met
with.
Old brick walls, on their northern faces especially, yield
Lecanora galactina, L. exigua. Buellia canescens, Lecidea lucida,
and Urceolaria scruposa, among other forms ; while Lecanora
saxicola prefers the upper surface of the wall-top. The cement
joints and rendering of the walls are the favourite stations of
H