Fissidens fontanus
Fissidens littlei
fissidens moss, water pocket moss
little's fissidens moss
usually profusely branched;
axillary hyaline nodules absent;
central strand absent.
unbranched and sparingly branched;
axillary hyaline nodules absent;
central strand 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 8 pairs, ligulate, obtuse-apiculate to acute, to 1.5 × 0.25 mm;
dorsal lamina narrowed proximally, ending at insertion or slightly decurrent;
vaginant laminae 1/2–2/3 leaf length, ± equal, minor lamina ending on or near margin;
margin crenulate, often irregularly so on vaginant laminae, elimbate;
costa ending 3–5 cells before apex, bryoides-type;
lamina cells 1-stratose, distinct, mammillose, firm-walled, irregularly quadrate to hexagonal, oblate on margin, 8–10 µm, somewhat larger, ± oblong in proximal parts of vaginant laminae.
0.5–0.6 mm.
1.4–1.8 mm.
gonioautoicous and cladautoicous;
perigonia and perichaetia on short axillary branches, 1–5 per leaf axil, sometimes on elongate, axillary branches.
rhizautoicous and gonio-autoicous;
perigonia gemmiform and on elongate stems.
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 0.5 mm long;
peristome teeth anomalous, undivided, papillose;
operculum to 0.3 mm.
mitrate, smooth.
cucullate, smooth, 0.3 mm.
18–27 µm.
8–11 µm.
1–5 per leaf axil, inconspicuous.
1 per perichaetium.
Fissidens fontanus
Fissidens littlei
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.)
This rare Fissidens, named in honor of the American botanist Elbert Little, is known only from the type locality and was recently re-discovered there by K. W. Allred (1998). The plants are pale green, probably the result of their occurrence in small pocketlike depressions where direct sunlight does not penetrate. The species has been confused with F. amoenus, but differs from the latter by its elimbate leaves, slightly smaller, mammillose laminal cells, oblate marginal cells, absence of enlarged pellucid cells in the proximal parts of the vaginant laminae, and undivided, papillose peristome teeth.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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