The Essex Naturalist
35
Starting in 1946, the British Bryological Society set up a scheme for the
acquisition of a voucher specimen to substantiate each record of a taxon from a
Watsonian vice-county. This collection has proved invaluable for checking the
correctness of records and for making adjustments due to taxonomic revisions,
for example when it is suddenly realised that what has hitherto been regarded as
a single taxon is actually comprised of two distinct taxa. When a taxon has not
been re-recorded from a vice-county for more than 50 years, a fresh voucher and
record are sought. The BBS Vice-county voucher collection (BBSUK) is
currently housed at the National Museum of Wales, Cardiff.
Several of the additional vice-county records reported in the following list,
have come to light as a result of further researching of herbarium material, while
others needed to be relisted because of taxonomic or nomenclatural changes.
Finally, some 98 records have been made as a result of new field work since
1974. These can mostly be attributed to Tim Pyner, who in addition to making a
large number of new records generally, has now surveyed nearly all of the 400 or
so Essex parish churchyards. Many of the new discoveries are of species that
were probably there all the time but had been overlooked. Others however, have
resulted from the spectacular recolonisation of the county by sulphur dioxide
sensitive species, which began to return around 1980, in response to a dramatic
fall in atmospheric sulphur dioxide levels (Adams &. Preston 1992). Species in
this category are being added so rapidly that it would seem prudent to wait
another year or two before publishing a full Vice-county Check-list of Essex
Bryophytes. They include the epiphytic Orthotrichum striatum, O. stramineum
and O. tenellum, Ulota crispa s.s., Tortula papillosa, Zygodon conoideus,
Orthotrichum pulchellum, Metzgeria temperata, Metzgeria fruticulosa and Ulota
phyllantha, all formerly extinct in Essex. The latter four have never been
reported before, probably because being very sensitive to SO,, they were wiped
out before the early bryologists recorded their former presence. Of the terrestrial
and rupestral species, Hylocomium splendens, and the newly found Racomitrium
taxa are also likely to be returning due to lowered SO, levels.
One species has had to be deleted due to a redefinition. Marchantia alpestris
recorded extensively in the southern counties during the 1960s and 1970s, has
now been critically redefined, resulting in our Essex specimens being included in
M. polymorpha ssp. ruderalis (see Long 1995).
New additions resulting from herbarium material include Campylium
polygamum and Rhytidiadelphus loreus, both found as ample specimens in glass-
topped display boxes, in the PEM collection, and both collected by Percy
Thompson in Little Monk Wood, Epping Forest in 1912. Unfortunately, a good
specimen of Sphagnum papillosum, also in a glass-topped box collected by W R
Sherrin in 1925, "somewhere" in Epping Forest, cannot be localised to either
vice-county (see also Essex Naturalist 21: 229). A specimen of Bryum alpinum
collected by Edward Forster in a wet gravel pit by the King's Oak on the Forest
c1800, was mentioned in a paper by F J Chittenden, and was subsequently