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BFNA Title: Pleuroziopsaceae |
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PLEUROZIOPSACEAE
Ireland Robert
R. Ireland Plants glossy,
medium-sized to large, in loose to somewhat dense tufts. Stems
with a creeping primary stem producing an erect, frondose-dendroid secondary
stem, pinnately and bipinnately branched; lamellae on branches and branchlets
numerous, 1--4 cells high, attached to epidermal cells of stems and abaxial
surface of leaf bases and costa; lamellae cells smooth, hyaline, inflated,
thin-walled; rhizoids abundant on
primary and secondary stems, whitish or reddish brown, much
branched, papillose, those on
secondary stems branches and branchlets on apical cells of lamellae, usually
dichotomously branched, smooth; paraphyllia
and pseudoparaphyllia lacking; Secondary
stem leaves complanate to slightly concave, erect, oblong-ovate,
apiculate. Secondary stem branch and branchlet leaves erect-spreading,
long-decurrent; cells of decurrent regions many, hyaline, inflated; median
cells long, vermicular; costae single. Sexual
condition dioicous. Seta elongate.
Capsule lateral on stem, ovoid,
arcuate, cernuous; peristome hypnaceous, double, teeth trabeculate, cilia
lacking. Genus
1, species 1; temperate climates. The
family Pleuroziopsaceae (R. R. Ireland 1968) was established for the genus Pleuroziopsis
primarily because of the presence of the unique stem lamellae first
discovered by A. Noguchi (1952). The
lamellae are abundant on the branches and branchlets and in addition to being
attached to the stems, they are attached to the abaxial surface of the leaf
bases and proximal part of the costa.
Also, the pinnate and bipinnate branching pattern, the ovoid, arcuate,
cernuous capsule with a hypnaceous peristome and the lack of paraphyllia were
additional morphological characters making it distinct it from Climacium. Recently, D. H. Norris and M. S. Ignatov
(2000), discovered (1--)2--3-stratose longitudinal streaks (stem lamellae) on
the stems of Climacium dendroides plants growing intermixed
with Pleuroziopsis plants from Alaska. These stem lamellae are scattered along the stems of C. dendroides,
the only species of Climacium in which they were observed. Whether these lamellae are morphologically
similar to those of Pleuroziopsis is debatable. The lamellae of Pleuroziopsis,
which are numerous, are attached to the leaf bases, the costa and the
epidermal cells of the branch and branchlet stems, continuing proximally
toward the leaf below. The lamellae
of Climacium dendroides are not attached to the leaf bases or
costa but instead only to the epidermal stem cells. In addition to the lamellae the authors noted that the
structures referred to as paraphyllia in Climacium are rhizoids, just
as they are in Pleuroziopsis.
However, it is primarily because of
the stem lamellae that the authors believe Pleuroziopsis should
be placed back in the family Climaciaceae. SELECTED
REFERENCES Ireland, R. R. 1968. Pleuroziopsidaceae, a new family of
mosses. J. Hattori Bot. Lab. 31:
59--64. Noguchi, A. 1952.
Mosses of Climaciaceae. Oita
Daigaku Gakugeigakubu Kenkyu Kiyo 1: 65--77.
PLEUROZIOPSIS
E. Britton, Bryologist 9: 39. 1906 • Pleurozium, a pleurocarpous moss genus; Greek opsis,
appearance or likeness Climacium sect. Girgensohnia
Lindberg; Girgensohnia (Lindberg) Kindberg, not Girgensohnia
Bunge 1.
Pleuroziopsis ruthenica (Weinmann) E. Britton, Bryologist 9:
39. 1906 "ruthenicum" Hypnum
ruthenicum Weinmann, Bull. Soc. Imp. Natural. Moucou 18: 485.
1845; Girgensohnia ruthenica
(Weinmann) Kindberg Plants
light green with red secondary stems and branches, green or red branchlets,
4--8 cm, erect, frondose-dendroid, in loose to somewhat dense tufts arising
from stoloniferous primary stems matted with whitish or reddish-brown,
papillose rhizoids. Secondary stems with
pinnate and 2-pinnate branches, branches attenuate, 1.5--3.0 cm, branchlets
attenuate, 4--7 mm; lamellae apical cells round, elliptic, square, or
rectangular in cross-section, branched rhizoids often arising from the top
surface, smooth. Stem leaves
clasping stem, 3--4 ´ 1.5--2.5 mm, smooth or wrinkled, ovate,
apiculate or obtuse to acute, entire, long-decurrent with many hyaline,
inflated cells, 1-stratose, margins plane, costa single, weak, smooth, ending
near leaf middle, leaf cells smooth or minutely prorulose, cell walls
non-pitted or pits not evident, median cells vermicular, 40--81 ´
5--7 µm; proximal branch leaves similar to stem leaves, smaller, gradually
grading distally into leaves similar to branchlet leaves above; median
branchlet leaves 0.5--1.0 ´ 0.3--0.5 mm, plicate, ovate to ovate-lanceolate,
broadly acute, irregularly and strongly toothed to serrate from apex to leaf
middle, serrate to entire proximally, long-decurrent with many hyaline,
inflated cells, 1-stratose, margins plane or narrowly recurved near base,
costa single, strong, commonly dorsally toothed, ending below apex, leaf
cells smooth or minutely prorulose by projecting cell ends, cell walls
non-pitted or pits not evident, median cells vermicular, 28--45 ´
5--7 µm. Sexual condition
dioicous; archegonial and antheridial plants similar, perigonial and
perichaetial buds on stem near branches; perigonial bracts broadly ovate,
acute; perichaetial bracts ovate, acute to acuminate. Seta
orange to red, smooth, twisted, ca. 1.5 cm.
Capsule red, solitary,
ovoid, arcuate, cernuous, smooth, not contracted below mouth, 3 ´
1 mm; annulus none; operculum not seen, reported as long-conic, almost
rostrate; peristome hypnaceous, endostome as long as exostome, cilia lacking.
Calyptra cucullate, covering 1/2 capsule. Spores 12--24 µm, sometimes germinating inside capsule. Humus
on ground or logs along creeks and rivers, or other moist, shaded habitats;
15--550 m; w B.C.; w Alaska, nw Wash.; Asia. This
is a distinctive species somewhat reminiscent of Climacium because
they both have erect secondary stems arising from a creeping primary stem and
the plants occur in wet habitats. Pleuroziopsis is lighter green, more
slender in appearance with a frondose-dendroid habit, an ovoid, arcuate,
cernuous capsule with a hypnaceous peristome, the teeth with fine cross
striolations, compared to the coarser dendroid habit of Climacium that
has a cylindric, straight, erect capsule with narrow peristome segments that
are densely papillose. Another important feature differentiating Pleuroziopsis
from Climacium that was not stressed when the family
Pleuroziopsidaceae was described is the nature of branching that
distinguishes the two genera and the family Climaciaceae. In Pleuroziopsis, the plants are
erect from a creeping primary stem, just as they are in Climacium, but
they are also frondose-dendroid, i.e., they are flattened and the secondary
and tertiary branches are divided, often several times, so the plants are
noticeably frondose. In Climacium,
on the other hand, the plants are not flattened but the branches arise around
the distal end of the erect, secondary stem and the branches seldom, if ever,
produce branchlets. The capsules of the two genera are quite different (R. R.
Ireland 1968). However, the value at
the familial level is not as important since reduced peristomes are known to
occur in some families of pleurocarpous mosses, as M. S. Ignatov et al.
(1998) have pointed out for the Brachytheciaceae. OTHER
REFERENCES Ignatov,
M. S., H. Robinson and E. A. Ignatova.
1998. Studies on the exostome
of Brachytheciaceae (Musci). Arctoa
7: 153--188. Norris,
D. H. and M. S. Ignatov. 2000. Observations on stem surface anatomy in Climacium
and Pleuroziopsis (Climaciaceae: Musci). Arctoa 9: 151--154. |
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