Fissidens scalaris
Fissidens ventricosus
fissidens moss
unbranched and branched;
axillary hyaline nodules present;
central strand present.
unbranched and branched;
axillary hyaline nodules absent;
central strand weak.
as many as 16 pairs, oblong to lanceolate, acute to short-acuminate, to 1.3 × 0.25 mm;
dorsal lamina narrowed proximally, ending well above or at insertion;
vaginant laminae ± 4/5 leaf length, ± equal, minor lamina ending on or near margin;
margin ± entire to crenulate-serrulate, limbate on all laminae, limbidium variable, developed best on vaginant laminae, ceasing well before apex, limbidium cells 1-stratose;
costa ending 2–5 cells before apex to percurrent, bryoides-type;
laminal cells 1-stratose, distinct, smooth, somewhat bulging, firm-walled, irregularly quadrate to hexagonal, 9–14 µm, increasing somewhat in size and ± oblong in proximal parts of vaginant laminae.
as many as 35 pairs, lanceolate to oblong-lingulate, acute to obtuse-apiculate; to 5 × 0.9 mm;
dorsal lamina narrowed proximally, ending at insertion, not decurrent;
vaginant laminae 1/2–2/3 leaf length, equal;
margin ± entire, limbate on all laminae, limbidium reaching apex or ending a few cells before apex and a few cells above insertion of dorsal lamina, limbidial cells 3- to 6-stratose;
costa ± percurrent, bryoides-type;
laminal cells 1-stratose, or variably 2-stratose, smooth, slightly bulging, firm-walled, irregularly quadrate to hexagonal, 8–13 µm, ± twice as deep as wide.
2–6 mm.
stout, to 3 mm, geniculate.
rhizautoicous;
perigonia gemmiform, proximal to fertile and infertile stems, and as branches along horizontal parts of stems.
probably rhizautoicous;
perigonia not seen;
perichaetia on elongate stems.
theca exserted, erect, radially symmetric, 0.5–1.25 mm;
peristome anomalous, variable, even in same theca, teeth undivided, imperfectly divided or divided 4/5 their length, papillose distally, smooth proximally;
operculum 0.22–0.3 mm.
theca emergent, erect, radially symmetric, to 1.2 mm;
peristome bryoides-type;
operculum 0.4 mm.
cucullate, smooth, to 0.45 mm.
not seen.
20–26 µm.
23–40 µm.
1 per perichaetium.
1–2 per perichaetium.
Fissidens scalaris
Fissidens ventricosus
Fissidens scalaris, although widespread in the southern part of the United States, is infrequently collected. It is best distinguished by its dimorphic stems and undivided to deeply divided, papillose peristome teeth. B. E. Lemmon (1965) published photographs of the development of plants, including perigonial, perichaetial, and infertile stems, and peristome.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Fissidens ventricosus occurs along the Pacific Coast of North America and at a disjunct site in northern Idaho (see map in R. R. Ireland and W. B. Schofield 1967). It is distinguished by its aquatic habitat, strongly limbate leaves, variably 2-stratose laminal cells, short, thick, geniculate seta, and emergent capsule. Plants usually become black and covered with diatoms. The species might be confused with F. rigidulus Hooker f. & Wilson, but the latter, found in wet sites in the Americas from Chile north to Mexico but not known in the United States, has much smaller laminal cells and a long seta characteristic of terrestrial species. The calyptra of F. ventricosus is cucullate according to Ireland and Schofield.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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