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asplenium fissidens moss

fissidens moss, pygmy pocket moss, slender pocket-moss

Habit Plants to 250 × 4 mm. Plants to 2.5 × 2 mm.
Stem

unbranched and sparingly branched;

axillary hyaline nodules weak;

central strand present.

unbranched;

axillary hyaline nodules absent;

central strand absent.

Leaves

in as many as 25 pairs, often undulate, mostly lingulate, rounded to obtuse to broadly acute, sometimes apiculate, to 4 × 0.5 mm;

dorsal lamina narrowed proximally, ending before or at insertion, not decurrent;

vaginant laminae 1/2–3/4 the leaf length, unequal, minor lamina of most leaves rounded and free distally, or narrowed distally and ending on or near costa;

margin ± entire to crenulate-serrulate, sometimes unevenly so distally, elimbate except for a weak limbidium in the proximal parts of vaginant laminae, limbidial cells 1-stratose;

costa ending several cells before apex, oblongifolius-type, distal part of leaf in transverse section showing enlarged cells arranged in a single row;

laminal cells of dorsal and ventral laminae 1-stratose, distinct, smooth, lenticularly thickened but appearing bulging, firm-walled, irregularly hexagonal, 7–12 µm long;

juxtacostal and interior proximal cells of vaginant laminae 1-stratose, smooth, plane, quadrate to ± oblong, larger;

medial marginal cells of vaginant laminae ± elongate, oriented obliquely.

as many as 4 pairs, lanceolate to oblong-lanceolate, acute to obtuse-apiculate, to 2.1 × 0.4 mm;

dorsal lamina ending before insertion;

vaginant laminae 2/5 leaf length, unequal, minor lamina narrowed, ending on or near costa;

margin of dorsal and ventral laminae ± entire to crenate-serrulate, crenate-dentate on vaginant laminae, elimbate;

costa percurrent to ending 2–3 cells before apex, bryoides-type;

laminal cells distinct, smooth, plane, firm-walled, irregularly quadrate to irregularly hexagonal, 10–15 µm, marginal cells slightly smaller, vaginant laminal cells somewhat larger with 2–3 intralaminal rows irregularly elongate.

Seta

to 6 mm.

2–9 mm.

Sexual condition

dioicous;

perigonia and perichaetia on elongate stems;

naked archegonia at times in axils of distal leaves.

rhizautoicous;

perigonia gemmiform, proximal to perichaetial stems or scattered over protonemata.

Capsule

theca ± erect, radially symmetric to slightly arcuate, bilaterally symmetric, to 1.5 mm;

peristome taxifolius-type;

operculum ± as long as theca.

theca exserted, erect, radially symmetric, infrequently slightly arcuate, bilaterally symmetric, to 0.7 mm;

operculum 0.4–0.6 mm;

peristome scariosus-type.

Calyptra

cucullate, smooth, 1–1.7 µm. Spores 7.5–12 µm.

cucullate, smooth, 0.5 mm.

Spores

11–14 µm.

Sporophytes

1–2 per perichaetium, orange-red.

1 per perichaetium.

Fissidens asplenioides

Fissidens exilis

Habitat Sandstone ledges and crevices in moist ravines and grottoes, usually along streams and waterfalls Bare, damp soil of shaded banks and in seepage areas
Distribution
from FNA
AL; GA; KY; LA; MS; NC; SC; Mexico; Central America; South America; West Indies; Asia; Africa; Atlantic Islands (Macaronesia); Pacific Islands (New Zealand); Australia
from FNA
AL; IL; IN; KY; MD; ME; MI; MO; NC; NJ; NY; OH; PA; TN; VT; QC; Europe; Asia; Africa [Introduced in North America; also introduced in West Indies]
Discussion

Fissidens asplenioides, usually a robust species, is recognized by leaves typically curled tightly inward from the tips when dry, a minor lamina that in most leaves is rounded distally and attached more or less only along costa, lenticularly thickened dorsal and ventral laminal cells, elongate medial marginal cells of the vaginant laminae oriented obliquely, and oblongifolius-type costa which in the distal part of the leaf in transverse section shows a single row of enlarged cells. The oblongifolius-type costa, found in F. asplenioides and F. santa-clarensis, is unique to sect. Amblyothallia of subg. Pachyfissidens (R. A. Pursell and M. A. Bruggeman-Nannenga 2004). Subterranean, multicellular, irregularly globose, rhizoidal gemmae have been reported in Macaronesian specimens of F. asplenioides.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Fissidens exilis, first reported for North America by W. C. Steere (1950), is probably inadvertently introduced from Europe. It can be distinguished from all other tiny Fissidens in the flora area by the 2–3 rows of irregularly elongate intralaminal cells in the vaginant laminae. Plants of this species would be easily passed over were it not for the persistent protonemata that often form dark green velvetlike carpets over the substrate and the numerous sporophytes that are produced. The gemmiform perigonia are often seen scattered over the protonemata. B. H. Allen et al. (2004) have reviewed and mapped the distribution of F. exilis in North America.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 27, p. 337. FNA vol. 27, p. 355.
Parent taxa Fissidentaceae > Fissidens Fissidentaceae > Fissidens
Sibling taxa
F. adianthoides, F. amoenus, F. aphelotaxifolius, F. appalachensis, F. arcticus, F. bryoides, F. bushii, F. closteri, F. crispus, F. curvatus, F. dubius, F. elegans, F. exilis, F. fontanus, F. grandifrons, F. hallianus, F. hyalinus, F. leptophyllus, F. littlei, F. minutulus, F. obtusifolius, F. osmundioides, F. pallidinervis, F. pauperculus, F. pellucidus, F. polypodioides, F. santa-clarensis, F. scalaris, F. serratus, F. subbasilaris, F. sublimbatus, F. submarginatus, F. taxifolius, F. taylorii, F. ventricosus, F. zollingeri
F. adianthoides, F. amoenus, F. aphelotaxifolius, F. appalachensis, F. arcticus, F. asplenioides, F. bryoides, F. bushii, F. closteri, F. crispus, F. curvatus, F. dubius, F. elegans, F. fontanus, F. grandifrons, F. hallianus, F. hyalinus, F. leptophyllus, F. littlei, F. minutulus, F. obtusifolius, F. osmundioides, F. pallidinervis, F. pauperculus, F. pellucidus, F. polypodioides, F. santa-clarensis, F. scalaris, F. serratus, F. subbasilaris, F. sublimbatus, F. submarginatus, F. taxifolius, F. taylorii, F. ventricosus, F. zollingeri
Name authority Hedwig: Sp. Musc. Frond., 156. (1801) Hedwig: Sp. Musc. Frond., 152, plate 38, figs. 7–19. (1801)
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