large, succubous, opposite or alternate, distichous, patulous or
devexo-seound, oblique, rarely acute, usually rotundate or truncate,
dentate or spinose, rarely entire ; marginal teeth or cilia acute,
ending in a single, sharp-pointed, conical cell ; antical margin
decurrent, recurved or revolute ; postical margin arcuate, rotundate,
sometimes semicircular, plane, towards the base reflexed,
margin dentato-spinose or ciliate, very rarely entire. Cells
medium size or rather large, rarely small, subquadrate-hexagonal,
only at the base oblong, very rarely all elongate ; trigones almost
always large and conspicuous ; cuticule smooth. Stipules normally
wanting, in some species mere scales, in others everywhere present,
small, entire or unequally plurifid, segments often flexuose. In florescence
dioicous. Androecia spicate, linear or fusiform, terminal
or at the middle ; perigonial bracts smaller than the leaves, ventricose,
closely imbricated, in two rows. Antheridia oval, 1 to 10,
usually 2 or 3. Female flowers terminal on the chief stem or
branches, or axillary from the growth of innovations. Bracts Ç
alternate, imbricate, transverse, erect, ventrioose-sacoate, 1-4 pairs,
free, larger and broader than the leaves. Pistillidia numerous
(25-70). Perianth more or less projecting, a little longer than
the bracts, free, laterally compressed at right angles to the plane
of the stem, campanulate or longer, and obconico-cylindrical or
clavate, erect or decurved at the apex, leptodermous, mouth wide,
obliquely truncate, rotundate or bilabiate, entire, dentate, or
ciliate. Calyptra free, included, about half the size of the
perianth, globose or oval-globose, leptodermous, slightly carnose
near the base, where it is surrounded by the sterile pistillidia.
Pedicel firm, about 10 cells in diameter, usually short, in a few
species elongate. Capsule large, globose or oval-globose, coriaceous,
dividing down to the base into 4 valves, valves sometimes
bilobed, 3-8 layers thick. Elaters bispiral, long, deciduous,
attached to the centre of the valves.
1. Plagiochila Stabler!, Pearson.
Plagiochila Siableri, Pears, in Jour, of Bot. Ju n e (1890).
Dioicous, loosely cæspitose, small, pale to brownish-green in
colour. Stems creeping, simple or irregularly branched ; branches
ascending ; radiculose, rootlets few, single, white. Leaves imbricate
or distant, bifarious, alternate, horizontal or patent-divergent,
largest near tbe middle of the stem, very slightly or not at all
deourreut antioally, plane or slightly concave, ohlong-quadrate,
oval or subcuneate, bidentate to about one-fourth, retuse or entire,
margin quite entire ; texture somewhat thick ; cells from moderate
to largish in size, roundish-quadrate ; walls thick, angles
thickened. Stipules evident, simple or bifid, segments subu'ate.
Dimensions.—Stems ^ inch long, with leaves 1'25 mm. wide;
diameter of stem 0'15 mm. ; leaves 0’7 mm. x 0'5 mm., 0'5 mm.
X 0'5 mm., 0'7 mm. x 0'45 mm. ; segments 0'2 mm., 0'6 mm.
x 0’5 mm., 0'7 mm. x 0'55 mm. ; segments O'l mm. ; cells
0 04 mm. x 0'045 mm., 0'04 mm. x 0’04 mm., 0'085 mm.
X 0’04 mm., 0'035 mm. x 0'035 mm.; stipules 0'225 mm.
x 0'05 mm., 0'2 mm. x 0'08 mm., 0'2 mm. x 0'04 mra.
H ab.— On rooks near Fall, Rydal Park, Rydal, Westmorland,
Mr. George Stabler, Sept. 1877.
O bs.—Although the small flagelliferous varieties of P. spinulosa
(Dicks.) and P. punctata, Tayl. are numerous, P. Stableri cannot
be confounded with any of them, the almost horizontal insertion
of the bidentate, retuse, or entire leaves, wliich are nearly plane,
and their much larger cells at once distinguish the species.
P. tridenticulata, Tayl., which has usually bidentate leaves,
oblong-oval in shape, with a very narrow base and small cells, is
very distinct.
P. exigua, Tayl. has very deourrent leaves of a different sliape,
with an extremely narrow base ; cells much smaller.
Pedinopliyllutn internqdum (Nees), with wliich it agrees somewhat
in the insertion of its leaves, is a much more robust plant,
with usually entire leaves and less evident stipules.
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