Fissidens fontanus
Fissidens pallidinervis
fissidens moss, water pocket moss
pale-nerve fissidens moss
usually profusely branched;
axillary hyaline nodules absent;
central strand absent.
branched and unbranched;
axillary hyaline nodules absent;
central strand weak or absent.
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 18 pairs, lingulate to lanceolate, rounded to obtuse to broadly acute, to 1 × 0.25 mm;
dorsal lamina narrowed or rounded proximally, ending at insertion, not decurrent;
vaginant laminae ± 1/2–2/3 leaf length, ± unequal, minor lamina ending near margin;
margin serrulate, limbate, ± entire in proximal 1/3–1/2 of perichaetial and subtending 1–2 pairs of leaves, limbidium sometimes indistinct, limbidial cells 1-stratose;
costa ending 3–25 cells before apex, often spurred distally, bryoides-type;
laminal cells 1-stratose, pluripapillose, obscure, firm-walled, irregularly quadrate to hexagonal, 4–8 µm, in transverse section usually twice as deep as wide.
0.5–0.6 mm.
to 2 mm.
gonioautoicous and cladautoicous;
perigonia and perichaetia on short axillary branches, 1–5 per leaf axil, sometimes on elongate, axillary branches.
rhizautoicous, cladautoicous, rarely gonioautoicous.
theca 0.5–0.6 mm, erect, radially symmetric;
peristome anomalous, irregularly divided, ± incomplete, often truncate, papillose;
operculum as long as seta.
theca exserted, erect, radially symmetric, to 0.6 mm;
peristome scariosus-type;
operculum 0.3 mm.
mitrate, smooth.
cucullate, ± prorate, 0.3 µm. Spores 9–14µm.
18–27 µm.
1–5 per leaf axil, inconspicuous.
1–2 per perichaetium.
Fissidens fontanus
Fissidens pallidinervis
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 pallidinervis and F. elegans are the only species of the genus in North America with small, obscure, pluripapillose laminal cells. Fissidens pallidinervis, however, is distinguished by a rounded to broadly acute leaf apex, and a limbidium restricted to the lower parts of vaginant laminae of perichaetial and one or two pairs of subtending leaves. Axillary, stalked, multicellular, clavate gemmae have been reported in Japanese collections of F. pallidinervis.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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