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fissidens moss

fissidens moss, water pocket moss

Habit Plants to 25 × 3.5 mm. Plants to 120 × 6 mm.
Stem

usually branched;

axillary hyaline nodules absent;

central strand present.

usually profusely branched;

axillary hyaline nodules absent;

central strand absent.

Leaves

as many as 25 pairs, often undulate, oblong to lanceolate, obtuse to acute, often apiculate, to 3.5 × 0.7 mm;

dorsal lamina truncate-rounded proximally, ending at insertion, not decurrent;

vaginant laminae 2/3 the leaf length, ± unequal, minor lamina ending near margin;

margin crenulate to crenulate-serrulate but unevenly serrate at leaf apex, elimbate;

costa ending a few cells before apex to percurrent, taxifolius-type;

laminal cells irregularly 2-stratose in dorsal and ventral laminae, ± obscure, smooth, bulging, firm-walled, rounded-hexagonal, 7–10 µm, 3–4 rows of marginal cells thinner, walls slightly thicker, forming a pale marginal band.

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.

Seta

to 11 mm.

0.5–0.6 mm.

Sexual condition

dioicous;

perigonia on short axillary branches and elongate stems;

perichaetia on short axillary branches, mostly near proximal ends of stems.

gonioautoicous and cladautoicous;

perigonia and perichaetia on short axillary branches, 1–5 per leaf axil, sometimes on elongate, axillary branches.

Capsule

theca slightly inclined, slightly arcuate, bilaterally symmetric, to 1.8 mm;

peristome taxifolius-type;

operculum 1–1.4 mm.

theca 0.5–0.6 mm, erect, radially symmetric;

peristome anomalous, irregularly divided, ± incomplete, often truncate, papillose;

operculum as long as seta.

Calyptra

cucullate, smooth, 1.8 mm.

mitrate, smooth.

Spores

13–20 µm.

18–27 µm.

Sporophytes

1 per perchaetium.

1–5 per leaf axil, inconspicuous.

Fissidens dubius

Fissidens fontanus

Habitat Soil and humus, bases of trees, decaying wood, rocks and boulders in moist, shaded sites Attached to various substrata in stagnant and flowing water, and in coastal estuaries
Distribution
from FNA
AK; AL; AR; AZ; CA; CT; DE; FL; GA; IA; IL; IN; KS; KY; MA; ME; MI; MN; MO; MS; NC; NE; NH; NY; OK; PA; SC; TN; TX; VA; VT; WI; WV; NB; NF; NS; ON; QC; Mexico; Central America; West Indies; Europe; Asia; Pacific Islands
[WildflowerSearch map]
from FNA
AL; AR; AZ; CA; CT; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; ME; MI; MN; MO; MS; MT; NC; NJ; NM; NY; OH; OK; OR; PA; RI; SC; TN; TX; VA; WA; WI; WV; BC; ON; Mexico; Central America; West Indies; Europe; Africa
[WildflowerSearch map]
Discussion

In contrast to Fissidens adianthoides, F. dubius has smaller, irregularly 2-stratose, obscure laminal cells. Subterranean, irregularly globose, multicellular rhizoidal gemmae have been reported for F. dubius as well as F. osmundioides and F. taxifolius in Europe and Japan. Z. Iwatsuki and T. Suzuki (1982) cited the occurrence of dwarf male plants (small perigonial stems located on the leaves of perichaetial plants) in Japanese specimens.

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

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.)

Source FNA vol. 27, p. 340. FNA vol. 27, p. 343.
Parent taxa Fissidentaceae > Fissidens Fissidentaceae > Fissidens
Sibling taxa
F. adianthoides, F. amoenus, F. aphelotaxifolius, F. appalachensis, F. arcticus, F. asplenioides, F. bryoides, F. bushii, F. closteri, F. crispus, F. curvatus, 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. exilis, 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
Synonyms F. adianthoides var. semicristatus, F. cristatus, F. cristatus var. winonensis, F. decipiens var. winonensis, F. floridanus Skitophyllum fontanum, Octodiceras julianum var. ohioense, F. debilis, F. julianus
Name authority P. Beauvois: Prodr. Aethéogam., 57. (1805) (Bachelot de la Pylaie) Steudel: Nomencl. Bot. 2: 166. (1824)
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