New Charophyte (Stonewort) and Bryophyte records
Musci
Schistidium crassipilum
TQ(51)39 373,933 18 Chingford, All Saints churchyard, on concrete wall, 11 January 1998.
Tim Pyner.
TQ(52)52 521,241 19 Stansted Mountfitchet, St Mary's churchyard, on limestone
gravestones and tombs. 5 November 1998. Tim Pyner.
The taxon previously known as Schistidium apocarpum has been split (1996) into 31 different
critical 'species' by H. Blom, thirteen of which have been recorded for the British Isles from existing
herbarium material. The commonest taxa in this group are supposed to be S. apocarpum s.s. [S.
apocarpum (Hedw.) Bruch & Schimp.] and S. crassipilum Blom. So far however, only the latter has
been recorded for Essex. The two differ in the marginal cells of the leaf base, those of S. crassipilum
having transverse walls more strongly thickened than the longitudinal walls (more or less the same
thickness in S. apocarpum) and in spore size, those of S. crassipilum being mostly smaller than
11 Jim in diameter and those of S. apocarpum mostly exceeding 1 1p.m. They also differ in the shape
of the cells on the outside of the lower half of the capsule, shortly rectangular in S. crassipilum,
isodiametric or wider than long in S. apocarpum. The new segregates of the complex are keyed,
described and illustrated by Hans Blom in Nyholm (1998), and a convenient key to the 13 British
taxa recorded so far is given in Smith (2000).
References
NYHOLM, E. (1998) Illustrated Flora of Nordic Mosses. Fasc. 4: 287-309.
SMITH, A.J.E. (2000) The Schistidium apocarpum complex in the British Isles. British Bryological Society
Bulletin 74: 42-49.
Essex Naturalist (New Series) 20 (2003)
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