148
THE ESSEX NATURALIST
Lecanora atra (Huds.) Ach.
Very rare on sandstone. 51/69.
A few depauperate specimens on horizontal surface of chest-tomb in
churchyard of All Saints', Hutton (1974, PME-B).
L. calcarea (L.) Sommerf.
Scarce on limestone. 51/69, 79.
Horizontal surfaces of chest-tombs and sloping surfaces of walls of All
Saints' Church, Hutton (1974, PME-B) and St Mary's Church, Runwell
(1974, PME-B). The horizontal surface of a chest-tomb at St Mary's
Church, Runwell, bears a community referable to the Lecanoretum
calcareae. It consists of Buellia epipolia, Caloplaca citrina, C. heppiana,
Lecanora calcarea (dominant), L. campestris, L. crenulata, L. dispersa,
Verrucaria nigrescens, V. Sphinctrina and other pyrenocarpous lichens.
L. campestris (Schaer.) Hue
Frequent on limestone, asbestos-cement, concrete, mortar and brick.
51/68, 69, 79.
On concrete path, 117, Norsey Road, Billericay (1971, PME-B); lime-
stone gravestones and wall of All Saints* Church, Hutton (1971, PME-B);
concrete, mortar and brick, Hutton (1971, PME-B); asbestos-cement shed
roof, Botney Hill Farm, Little Burstead (1974, PME-B); concrete roofing
tiles, One Tree Hill (1974, PME-B); tops and sides of limestone gravestones
and wall of St Mary's Church, Runwell (1974, PME-B).
L. conizaeoides Nyl. ex Comb.
Abundant on deciduous trees, palings, sandstone and other siliceous
substrates; much less common on coniferous trees. 51/68, 69, 78, 79, 52/70.
By far the commonest corticolous lichen in the area, very frequently
being the only lichen present on trees (invariably so on young trees) and
palings, especially within the urbanized areas.
L. crenulata (Dicks.) Hook.
Scarce on limestone and asbestos-cement. 51/69, 79.
Asbestos-cement roof, Havering's Grove (1972, SJH); top of limestone
headstone and horizontal surface of chest-tomb, St Mary's Church, Run-
well (1974, PME-B).
L. dispersa (Pers). Sommerf.
Abundant on concrete, mortar, asbestos-cement, limestone, marble;
occasional on bark (especially Ulmus and Salix) and decorticate wood and
palings; also recorded on roofing-felt. 51/68, 69, 78, 79, 52/70.
This species is one of the commonest lichens in the area. The record on
roofing felt is due to lime run-off. It is usually the first coloniser of man-
made calcareous substrates, forming, together with such species as
Candelariella aurella, the pioneer Lecanorion dispersae federation.
L. exapllens Ach.
Occasional on Ulmus, Fraxinus and Salix. 51/68, 69, 79, 52/70.