Photo
by Dr M Lueth ©.
*1: Calenick near
Truro, 1960, JAP
(BBSUK) (Paton 1969a:
754).
*2: Trehane near
Probus, 1857, ES (TRU) (Paton 1969a:
754).
P. ruthei
was treated as a valid species by Smith (1978: 626) and
Blockeel & Long (1998: 152) and as var. undulatum of P. denticulatum by Smith
(2004: 872) although the latter author commented that 'it is a
very poorly defined taxon'. Lewinsky (1974: 204) found P. ruthei ' to be very
constant' in Denmark and
'therefore easy to recognise', but she apparently examined
only seven specimens. My own experience of it is more like
that of Paton (1969a: 754), who commented that it is 'An
unsatisfactory species which may only be a wet habitat form of
P. denticulatum'.
Likewise, Laflin (1971: 687) noted that 'Examination of more
than a hundred Warwickshire gatherings of ruthei type makes me
strongly suspect that British P. ruthei is no more
than a wet habitat form of P.
denticulatum.'
Habitat notes from Cornwall are as follows. More or
less acidic soil on banks and among rocks in and at edges of
deciduous woodland and groves, on laneside banks, on stream
banks. Soil and leaf litter in Grey Willow carr (often in wet
sites), Grey Willow scrub near china clay quarries. Edge of
scrub on old mine site. Acid soil among rocks on 'hedges' e.g.
beside lanes and between pastures, on bank near reservoir and
at edge of pasture. Steep clay soil of ditch bank beside china
clay spoil, part shaded. On ground litter or fern tussocks on
wet ground inside Grey Willow carr or wet deciduous woodlands.
Base of Juncus and
Molinia caerulea in
ungrazed, overgrown acid mire (with Calypogeia fissa, Chiloscyphus
pallescens). Other associates recorded include Brachythecium
rivulare,
Kindbergia praelonga, Hookeria lucens, Lophocolea
bidentata, Mnium
hornum,
Plagiothecium nemorale, Rhizomnium punctatum,
once Fissidens bryoides
var.
caespitans. Also near Chrysosplenium
oppositifolium.
Commonly/frequently c.fr.: capsules immature 1,
3-7, (9), 11; dehiscing 1, 5-9; dehisced 1-5, 7-9, 11,
12.