THE LICHEN FLORA OF THE BASILDON AREA 147
C. ochrochlora Florke
Rare on Aesculus. 15/69.
Bole of Aesculus at edge of Norsey Wood, Norsey Road, Billericay
(1972, SJH).
C. subulata (L.) Web.
Scarce on loamy soil. 51/69, 52/70.
Railway embankment, Hutton (1971, PME-B); Galleywood Common
(1972, IMH).
Evernia prunastri (L.) Ach.
Very rare on Fraxinus and Salix. 51/69, 52/70.
A single depauperate specimen (c. 1 cm long) on old Fraxinus stump,
Thrift Wood, Bicknacre (1972, IMH); a single depauperate specimen of
similar size on a prostrate Salix at edge of drained pond, Norsey Farm,
Billericay (1973, PME-B).
Hypogymnia physodes (L.) Nyl.
Locally frequent on boles of Salix, Quercus, Fraxinus and Aesculus; also
on palings and planks. 51/68, 69, 52/70.
On horizontal surfaces of garden fence, 117, Norsey Road, Billericay
(1971, IMH); Fraxinus stumps, Thrift Wood, Bicknacre (1972, IMH);
bole of Quercus overhanging pond, Norsey Farm, Billericay (1972, IMH);
on Salix beside stream, Galleywood Common (1972, IMH); bole of
Aesculus at edge of Norsey Wood, Billericay (1972, SJH); boles and lower
parts of inclined mossy trunks of Salix beside drained pond, and on
wooden plank of shed, Norsey Farm, Billericay (1973, PME-B); bole of
Quercus, Stock (1973, IMH); boles and lower parts of inclined trunks of
Salix in sheltered hollow and by water, One Tree Hill (1974, PME-B).
This species is the commonest foliose member of the Physodion federation,
which is extremely fragmentary and simplified within the area, usually
consisting of very few or no other species than Hypogymnia physodes.
The garden fence of 117, Norsey Road, Billericay was erected in 1967
and now has several vigorously growing thalli (up to two centimetres in
diameter) of Hypogymnia physodes on the horizontal surfaces which were
not creosoted. By contrast, the thalli on bark on the bole of a Quercus,
although overhanging water and situated only about one hundred metres
away, have not measurably increased in size since 1971. This compares
favourably with studies I have made in the polluted regions of West
Yorkshire, where Hypogymnia physodes occurs sparingly as stunted
specimens on the boles of trees on the outskirts of the urbanised areas,
but occurs nearer to urban centres on lignicolous substrates.
Lecania erysibe (Ach.) Mudd
Occasional on asbestos-cement; rare on limestone. 51/68, 69, 79.
Corrugated asbestos-cement roof, 6 Fairfield Avenue, Hutton (1971,
PME-B); corrugated asbestos-cement roofs, disused barracks, Langdon
Hills (1974, PME-B) and Botney Hill Farm, Little Burstead (1974, PME-B);
limestone wall of St Mary's Church, Runwell (1974, PME-B).