*1: Soil between granite rocks, Zennor, 1961, JAP (BBSUK) (Paton 1969a:
736, Smith & Whitehouse 1978: 44, Hill 1979: 30), as B. dunense. Zawn Reeth
near Land's End, 1964, JAP (BBSUK) (Paton 1969a:
736), as B. bicolor. There are
numerous older records.
*2: Marsland Mouth, N. of Morwenstow, 1949, TL (Paton
1969a: 736), as B. bicolor. Path,
1966, JAP (BBSUK)
(Smith & Whitehouse 1978: 44, Hill 1979: 30), as B. dunense. There are
numerous older records.
Holyoak (2003b, 2004: 254-255) gave reasons for
bicolor, B. dunense and B. barnesii as forms of
the same variable species, for which the correct name is B. dichotomum. It is
very variable in morphology in C&S as in other parts of
BI. Phenotypes with a long excurrent costa and large leafy
bulbils in leaf axils ('B. dunense') intergrade
with acute-leaved muticous forms that have several smaller
bulbils in each leaf axil ('B. bicolor') and they in
turn intergrade with blunt-leaved muticous forms having up to six
bulbils per leaf axil ('B. barnesii'). More than
one of these phenotypes may be produced where parts of a
single population grow in adjacent dry and wet microhabitats,
implying considerable vegetative plasticity.
Notes on habitats in C&S for the 'B. bicolor phenotype'
and scarcer 'B. barnesii phenotype'
are as follows. Very common colonist of bare soil in wide
range of situations, including thin soil layers on paths,
tracks or over rocks, old tarmac, asbestos-cement or concrete.
Colonising bare soil in fields (arable and pastures) and
gardens, on slopes and banks on and above sea-cliffs, in
quarries, on old mine-spoil, gravel car parks, roadsides,
beside paths and tracks, on top of walls. Colonist of mud,
soil and firm clay exposed in inundation zones beside
reservoirs. Indifferent to lithologies, occurring over
serpentinite, granite, slates, china clay spoil, concrete, old
timber or old tarmac. Frequently occurs on small soil
accumulations around windows of old cars, also at times on
dumped rubbish such as decaying carpets.
Common associates include Barbula convoluta, Bryum argenteum, Bryum capillare, Bryum dichotomum, Ceratodon
Dicranella staphylina, Dicranella varia, Didymodon
Didymodon nicholsonii, Kindbergia
Pseudocrossidium hornschuchianum, Tortula truncatula.
Numerous others recorded e.g. Archidium
Bryum subapiculatuma, Dicranella
Didymodon tophaceus, Ephemerum serratum, Epipterygium
Pseudephemerum nitidum, Riccardardia
In 'B. bicolor phenotype'
and 'B. barnesii phenotype'
axillary bulbils abundant (all months), but quite often
absent. Brown rhizoidal tubers apparently frequent. Frequently
c.fr.: capsules immature 1-5, 8, 10-12; dehiscing 1-3, 5, 7,
8, 11, 12; dehisced 1-5.
Habitat notes on the 'Bryum dunense
phenotype' in C&S are as follows. This form is
characteristic of soil in bare patches on cliffs, banks,
tracks, paths and 'hedges' above sea-cliffs; also in very
short grassland on calcareous dune sand and on cliff slopes;
unshaded. Associates recorded: Acaulon muticum, Archidium
Brachythecium albicans, Bryum argenteum, Ceratodon
Microbryum davallianum, Phascum cuspidatum, Pseudocrossidium
Rhynchostegium megapolitanum, Syntrichia ruralis
Syntrichia ruralis var. ruralis, Tortella
Tortula viridifolia, Cerastium diffusum, Festuca rubra, Plantago coronopus;
torquescens. Other records of 'B. dunense' were as
follows. From partly bare patches of soil in grassland,
including with Festuca
rubra low on exposed sea-cliff (with Bryum bornholmense, Bryum subapiculatum).
Unshaded gravel area near estuary. Partly bare sandy soil in
churchyard near dunes. Partly bare patches of soil over
serpentinite, slates or granite (once over concrete), among
rocks, at edges of paths, on coastal headlands and at top of
sea-cliffs (associates include Ceratodon purpureus,
alternifolium, sometimes Bryum capillare, Trichostomum
Weissia sp., but a more rapid colonist than most of these
and hence often in pure patches). Inland on unshaded gravelly
track edge at base of slope of mine-spoil and at edge of
gravel car park. Inland on slope of earthy mine-spoil, almost
unshaded (with Bryum
Dicranella staphylina, Phascum cuspidatum
Trichodon cylindricus, Tortula truncata).
Soil in arable fields (flax-stubble, cereal stubbles, maize
stubble, weedy fallow), in several places including inland
sites (e.g. near Bodmin) and c.fr. (with Barbula convoluta, Bryum rubens, Dicranella
Dicranella staphylina, Trichodon
Fossombronia pusilla, Tortula truncatula).
The 'B. dunense phenotype'
was only recorded when axillary bulbils seen, these common.
Brown rhizoidal tubers apparently frequent. 'B. dunense phenotype'
occasionally c.fr.: capsules present 3, 5; immature 2, 4, 8,