*1: Carpets on heaps of
waste, old arsenic mine, Fernysplat Mills, Bissoe, SW. of
Truro, Apr. 1962, JAP (BBSUK) (Warburg 1963b:
496, Paton 1969a: 725).
In Cornwall this species usually grows as dense low
lawns of a distinctive very dark green colour, which often
extend over several square metres and locally cover tens of
square metres and largely exclude other bryophytes (for
atypical growth in large low tufts see below). Habitat notes
from Cornwall are as follows. Apparently a calciphile, that
appears to be closely associated with substrates rich in
copper or arsenic. It grows fully insolated or more often
partly to rather heavily shaded (especially at bases of
N.-facing walls) on substrates that may be free-draining to
rather damp (rarely permanently wet: see below). It occurs on
horizontal to vertical masonry e.g. of old walls (on stone,
mortar and concrete), thin soil over rocks and masonry, and
sometimes more extensively on soils where these receive
drainage from old mine buildings (especially those formerly
used for sorting metalliferous ores or as arsenic works). Also
recorded from old mine-spoil, on banks, paths and tracks on
old mining ground, in an old quarry, and around an old
smelting works on top of a sea cliff. Single records from low
on a church wall and a path near a church might also be
associated with metalliferous substrates. Among dunes at Upton
Towans it occurs widely on old tracks surfaced with mine-spoil
as patches of very low plants. NW. of Reskadinnick it occurs
on sparsely vegetated horizontal sand close to concrete of
ruins, the sand having been brought here from estuary of
Red River for recovery of
copper ores. Another atypical site near lower Red River might also be associated with
metalliferous residues. Here, H. recurvirostrum formed
large low tufts in the edge of a small stream, mixed with some
Bryum
pseudotriquetrum and close to Philonotis fontana, Equisetum palustre
and Juncus
effusus. On old mine sites it commonly forms extensive
pure patches. Bryum
pallescens is sometimes a characteristic associate,
growing out of the patches of H. recurvirostrum. Other
associates recorded include Didymodon
tophaceus.
The habitats of H. recurvirostrum in
Cornwall contrast markedly with those elsewhere in western
Britain and Ireland, where it is known mainly as a calcicole
of moist limestone ledges (often in the mountains), occurring
also on boulders and limestone pavement, and on hummocks and
gravelly ground in calcareous flushes (T.L. Blockeel in Hill
et al. 1992: 290).
In western Ireland it also
occurs on damp calcareous sandstone crags and on damp
calcareous sand in dunes (pers. obs.).
Not known fertile in Cornwall. Capsules are rare
in other parts of British
Isles (Blockeel loc.
cit.).
Near the landward edge of Upton Towans
it grows as extensive low patches on pathways that were
surfaced with metalliferous mine-spoil during the 1939-45 war,
with only a thin layer of compressed blown-sand now covering
the mine-spoil. In places it grows there with Petalophyllum ralfsii.
Chemical analyses of its substrates show that it can tolerate
high levels of Cu, Pb and Zn, and indeed simultaneous presence
of all three of these metals at high concentrations. All
substrates investigated were basic.
Analyses of substrates from
localities in Cornwall (metal
concentrations given as µg/g dry
weight):
LOCALITY (N samples) Cu
Pb
Zn
pH
Source
Upton Towans, vc1 (7)
251-4499
31-2242
354-15287
7.1-7.9
Rouen
(2000)
