Fissidens fontanus
Fissidens polypodioides
fissidens moss, water pocket moss
polypody fissidens moss
usually profusely branched;
axillary hyaline nodules absent;
central strand absent.
unbranched and sparingly branched;
axillary hyaline nodules absent;
central strand present.
in numerous pairs, lanceolate to linear-lanceolate, frequently somewhat falcate, acute, to 7 × 0.6 mm;
dorsal lamina narrowed proximally, usually ending before insertion;
vaginant laminae 1/3–1/2 the leaf length, unequal, minor lamina usually rounded and free distally or narrowed and ending on or near costa;
margin ± entire, elimbate;
costa ending 15–35 cells before apex, bryoides-type;
laminal cells usually 1-stratose, sometimes 2-stratose juxtacostally, quadrate to short-oblong to hexagonal, smooth, slightly bulging, ± firm-walled, 15–23 × 10–18 µm in dorsal and ventral laminae, juxtacostal cells largest.
as many as 80 pairs, somewhat undulate, oblong, obtuse to broadly acute, usually bluntly mucronate, to 4 × 1 mm;
dorsal lamina rounded proximally, ending at insertion;
vaginant laminae 1/2 the leaf length, acute, ± equal, minor lamina ending on or near margin;
margin entire but denticulate distally, elimbate;
costa percurrent to ending 2–4 cells before apex, taxifolius-type;
laminal cells 1-stratose, distinct, smooth, slightly bulging, firm-walled, irregularly hexagonal, 10–20 µm, larger juxtacostally, smaller at margin.
0.5–0.6 mm.
to 15 mm.
gonioautoicous and cladautoicous;
perigonia and perichaetia on short axillary branches, 1–5 per leaf axil, sometimes on elongate, axillary branches.
dioicous;
perigonia and perichaetia on short axillary branches and main stems.
theca 0.5–0.6 mm, erect, radially symmetric;
peristome anomalous, irregularly divided, ± incomplete, often truncate, papillose;
operculum as long as seta.
theca slightly inclined, radially symmetric or slightly arcuate, bilaterally symmetric, to 2.5 mm;
operculum about as long as theca.
mitrate, smooth.
cucullate, smooth, 1.5–1.55 mm.
18–27 µm.
9–11 µm.
1–5 per leaf axil, inconspicuous.
1–2 per perichaetium.
Fissidens fontanus
Fissidens polypodioides
Fissidens fontanus and F. hallianus are aquatic species usually found in stagnant or slow moving water, but at times emergent because of fluctuating water levels (H. A. Crum and L. E. Anderson 1981; P. G. Davison and D. E. Wujek 1999). Plants of both species are usually profusely branched, delicate, and feathery in appearance with leaves often 10 times or more as long as wide. Often plants are encrusted with diatoms. Stems and leaves might also appear black due to deposition of organic matter. When dry the leaves are unusually fragile so that when being prepared for herbarium storage it is best to float plants onto sheets prior to drying.
A suite of gametophytic and sporophytic characters distinguishes Fissidens fontanus. The unequal vaginant laminae are about 1/4–1/3 the leaf length, and minor lamina is round and more or less free distally. In addition, costa ends well below the leaf apex. In fertile specimens, the clusters of 1–5 axillary, inconspicuous, dark sporophytes in each perichaetium are distinctive. The sporophytes, more prevalent than thought, are caducous and are often found in the bottom of the herbarium packets. The short seta is equal in length to that of operculum, and peristome teeth are greatly reduced, often consisting of only the truncated, undivided basal parts.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Fissidens polypodioides is a robust species and has its greatest distribution in the neotropics and Asia. It is perhaps the handsomest species of the genus in the flora area. However, it might be confused with F. asplenioides, from which it is distinguished by taxifolius-type costa, leaves crisped but not curled tightly inward when dry, entire leaf margin, acute and more or less equal vaginant laminae, larger laminal cells that are not lenticularly thickened, and absent differentiated medial marginal cells in the vaginant laminae. The central strand is especially well developed. H. A. Crum and L. E. Anderson (1965, 1981) published illustrations of F. polypodioides and F. asplenioides that aid greatly in distinguishing the two.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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