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PTILIDIUM PULCHERRIMUM (WEB), HAMPE,
IN EPPING FOREST.
By JOSEPH ROSS.
[Read 24th February 1917.]
THE distribution of this liverwort is said, in MacVicar's
Handbook of British Hepatics (1912), to be from Derby to
Aberdeen, and the plant is termed "rare." Mr. W. R. Sherrin
tells me that it is recorded from South Somerset. Mr. W. E.
Nicholson, of Lewes, published in the last issue of the South
Eastern Naturalist a long (and clearly a complete) list of the
hepatics of the Tunbridge Wells district. In that list, P.
pulcherrimum does not appear, though P. ciliare, the allied
species, is included.
Authorities differ as to whether P. pulcherrimum is a dis-
tinct species or a variety of P. ciliare. The usual habitats of
the two plants are distinctive. P. ciliare is usually found on
wet moors : P. pulcherrimum on trunks of trees or about their
roots ; but neither is confined to such situations. I have
assumed that P. pulcherrimum is a definite species, but I have
not yet found P. ciliare growing.
P. pulcherrimum occurs on an oak not far from Cuckoo Pits,
a well-known area in the Chingford part of Epping Forest.
Map C in Mr. E. N. Buxton's Guide calls the locality Pear Tree
Plain. The oak is on the London clay, but bracken grows freely
at a short distance, and this may indicate the existence of gravel.
On the higher parts south and east, there are numerous evidences
of gravel digging. South of the spot where the oak grows is a
small open plain, marshy in winter ; and possibly this is actually
the Pear Tree Plain of Mr. Buxton's map. Two tracks lead
north from the plain, and these become water-logged on the
feast provocation, for the area is distinctly damp.
The oak on which P. pulcherrimum occurs is a few yards
west of one of the tracks, and leans in a pronounced degree to
the south. It is on the north side of the tree that the plant
grows. This is what one would expect ; for the northern side
is protected from the drift of London's smoke. At its base,
the trunk of the tree rises at an angle of about 75 degrees, and
four or five feet from the ground the angle is increased to about
45 degrees. The Ptilidium grows from about 11/2 feet from the