Fissidens dubius
Fissidens minutulus
fissidens moss
usually branched;
axillary hyaline nodules absent;
central strand present.
unbranched;
axillary hyaline nodules absent;
central strand present or absent.
as many as 25 pairs, often undulate, oblong to lanceolate, obtuse to acute, often apiculate, to 3.5 × 0.7 mm;
dorsal lamina truncate-rounded proximally, ending at insertion, not decurrent;
vaginant laminae 2/3 the leaf length, ± unequal, minor lamina ending near margin;
margin crenulate to crenulate-serrulate but unevenly serrate at leaf apex, elimbate;
costa ending a few cells before apex to percurrent, taxifolius-type;
laminal cells irregularly 2-stratose in dorsal and ventral laminae, ± obscure, smooth, bulging, firm-walled, rounded-hexagonal, 7–10 µm, 3–4 rows of marginal cells thinner, walls slightly thicker, forming a pale marginal band.
as many as 12 pairs, lanceolate to oblong-lanceolate, occasionally narrowly lanceolate, acute to rarely apiculate, to 1.2 × 0.2–0.3 mm;
dorsal lamina narrowed proximally, ending at or sometimes before insertion;
vaginant laminae 1/2 leaf length, ± equal, minor lamina ending on or near margin;
margin entire but serrulate to denticulate distally, limbate on all laminae, limbidium ending a few to several cells before leaf apex, not reaching proximal end of dorsal lamina, sometimes edged by 1 or more rows of quadrate cells in proximal part of vaginant laminae, limbidial cells 1-stratose;
costa ending a few cells before apex to percurrent, bryoides-type;
laminal cells 1-stratose, smooth, strongly bulging, ± obscure, firm-walled, irregularly quadrate to hexagonal, mostly 6.5–10 µm, in transverse section twice as deep as wide.
to 11 mm.
1–4.5 mm.
dioicous;
perigonia on short axillary branches and elongate stems;
perichaetia on short axillary branches, mostly near proximal ends of stems.
rhizautoicous.
theca slightly inclined, slightly arcuate, bilaterally symmetric, to 1.8 mm;
peristome taxifolius-type;
operculum 1–1.4 mm.
theca exserted, usually erect, radially symmetric, 0.2–0.8 mm;
peristome bryoides-type;
operculum 0.3 mm.
cucullate, smooth, 1.8 mm.
cucullate, smooth, 0.5 mm.
13–20 µm.
10–16 µm.
1 per perchaetium.
1–2 per perichaetium.
Fissidens dubius
Fissidens minutulus
In contrast to Fissidens adianthoides, F. dubius has smaller, irregularly 2-stratose, obscure laminal cells. Subterranean, irregularly globose, multicellular rhizoidal gemmae have been reported for F. dubius as well as F. osmundioides and F. taxifolius in Europe and Japan. Z. Iwatsuki and T. Suzuki (1982) cited the occurrence of dwarf male plants (small perigonial stems located on the leaves of perichaetial plants) in Japanese specimens.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Fissidens minutulus is often confused with an expression of F. bryoides. The two have similar habits, and both are found on rocks at edges of streams, although F. minutulus is found principally on limestone, while F. bryoides occurs mostly on acidic rocks. Moreover, the laminal cells of F. minutulus are small (6–10 µm), strongly bulging, and more or less obscure, unlike the somewhat larger, more or less plane, distinct cells of F. bryoides. In transverse section the laminal cells of F. minutulus are twice as deep as wide, while those of F. bryoides are more or less as deep as wide. Stems of F. minutulus are unbranched while those of F. bryoides are branched.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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