*1: Penlee Croft,
Mousehole, 1868, WC (PNZ) (Paton 1969a:
755).
*2: St Minver, 1879,
RVT (B) (Paton 1969a:
755).
Treated at species rank in the revision by Smith
(1997). However, lacunosum appears to
be little more than a robust form of H. cupressiforme to
which it is connected by intermediate plants, so Hill et al. (2008) treated
it as a variety.
'Var. tectorum' is connected
to var. lacunosum
by intermediate plants at some of its few Cornish localities
(SW76V, SW83F, in DTH). It is probably best
regarded as a straight-leaved variant of H. cupressiforme var. lacunosum unworthy of
even varietal separation.
Habitat notes from C&S are as follows.
Plentiful on calcareous sand of fixed dunes, typically in
short turf of dune-grassland or on sandy slopes above
sea-cliffs; also where blown sand rests on open coastal
hillsides. Associates recorded: Homalothecium
lutescens,
Pleurochaete squarrosa, Syntrichia ruralis
var.
ruraliformis,
Festuca rubra,
Holcus lanatus,
Plantago lanceolata, Senecio jacobaea
(seedlings), Thymus
polytrichus; rarely Amblystegium serpens
var. salinum, Brachythecium
glareosum. Thin soil over rocks (granitic, gabbro, slates,
serpentinite), attached to horizontal or gently sloping rock
surfaces and on edges of rocks or tops of boulders (also a few
records on top of old mortared-stone walls), on sea-cliffs,
exposed coastal headlands, heaths, heathy banks, unshaded
hilltops, bare patches in pastures and other acid grasslands,
in old quarries and on their spoil, heathy areas on old
mine-spoil, on unshaded 'hedges', often in short turf. Often
on distinctly acid soils. Locally frequent as colonist on
china clay spoil heaps and on clay soil of banks near working
china clay quarry, unshaded. Gravelly top of grave in
churchyard, unshaded. Sloping masonry low on wall of reservoir
dam, unshaded. Over old concrete, e.g. edges of runway of
disused airfield and on disused china clay dries. Unshaded
gravelly soil of disused railway track, well drained, on
bridge. On thin soil over rocks and on granite in open place
on heath; old quarry; often on acid soils. Soil over rocks
above sea-cliff; unshaded. In short turf and bare patches on
soil and thin soil over slaty rocks on unshaded slopes of
coastal headland. On thin, unshaded, partly bare soil over
slaty rock of upper part of low sea cliff. On low bank of
unshaded china-clay spoil above ditch. With open vegetation
cover on unshaded top of old stone wall around mine shaft.
Associates often include Campylopus
introflexus,
Dicranum scoparium,
Pseudoscleropodium purum; among many others recorded are
Bryum kunzei, Cephaloziella
divaricata, Grimmia
lisae, Lophozia
excisa, Polytrichum
juniperinum,
Scleropodium touretii, Tortula
viridifolia,
Tortula wilsonii,
Trichostomum brachydontium, Conocephalum
conicum, Cladonia
spp., low herbs (e.g. Aphanes) and low
grasses.
Infrequently c.fr. (about seven recent records);
capsules immature 10-12, dehiscing 1,
12.