LIMBELLA - AMBLYSTEGIACEAE
XXX. LIMBELLA (Müller Hal.) Brotherus., Bull. Bernice P. Bishop Mus. 40: 23. 1927 * [For limbate leaf margins]
John A. Christy
Hypnum sect. Limbella Müller Hal. in H. G. A. Engler, Forschungsr. Gazelle 5: 37. 1889; Hypnodendron subg. Limbella Brotherus
Plants 4--50 cm, coarse, prostrate or dendroid, forming yellow-green to blackish sods or mats. Stems 4--15(20) cm, dark reddish-brown to black, densely matted with dark reddish-brown rhizoids at base, often defoliate proximally; branching subpinnate distal to a more or less naked stem; branches 1--8(--13) cm, occasionally producing flagelliform branches; pseudoparaphyllia foliose; paraphyllia lacking. Stem leaves smooth, spreading, ovate-oblong or ovate-lanceolate, acuminate or cuspidate, keeled, somewhat contorted when dry, 1.5--3.5 mm, proximal leaves scale-like and erose, elongate-triangular to deltoid, plicate, tapering to an often subulate, flexuose tip; margins plane, 1-stratose, 1--2 cells wide, serrulate to serrate, occasionally entire, sometimes forming basal auricles 2--10 cells wide, with conspicuous, usually submarginal limbidia of (2--)4 layers of incrassate cells, usually disappearing near acumen, sometimes with spurs extending into the lamina, and often absent in the most proximal leaves; costa single, strong, percurrent to shortly excurrent; distal laminal cells subquadrate to rhomboidal, 3--36 x 3--18 /um, 1-stratose, smooth; basal cells mostly oblong, walls at insertion incrassate, sparingly pitted, often yellow, 7--77 x 3--18 /um. Branch leaves similar to stem leaves, but with limbidia strong, disappearing very near acumen, or confluent with costa, to 3.5 mm. Sexual condition dioicous. Perichaetial leaves erect, lanceolate, long-acuminate, squarrose, serrulate distally or entire, costate but lacking limbidia, 1--2.5 x 0.8--1 mm. Seta single, reddish-brown, straight or flexuose, often tortuose in aquatic plants, 1.5--3.5 cm, smooth. Capsule horizontal to cernuous, oblong-cylindric, asymmetrical, sometimes arcuate, reddish-brown, 1.5--3 mm, usually shrunken under the mouth when dry; exothecial cells quadrate to rounded-rectangular; stomata superficial; annulus of 2--3 rows of cells, deciduous; operculum conic-apiculate to rostrate; peristome hypnoid, exostome teeth 16, yellowish-brown, lanceolate, sometimes cribrose at base, cross-striolate below, papillose above, trabeculate at back; endostome hyaline or pale yellow, with high basal membrane, cilia appendiculate. Calyptra cucullate, naked, cylindric, early-deciduous. Spores 14--18 /um, minutely papillose, green.
Species 2 (1 in the flora): northwestern North America, Pacific Islands (Hawaii).
Species of Limbella previously have been included in Sciaromium (Mitten) Mitten, a synonym of Echinodium Juratzka (S. P. Churchill 1986).
SELECTED REFERENCES Christy, J. A. 1987. Limbella fryei (Williams) Ochyra distinct from L. tricostata (Sull.) C.M. (Musci: Amblystegiaceae). J. Hattori Bot. Lab. 63: 395--410. Ochyra, R. 1987b. On the taxonomy and family placement of the moss genus Limbella (C. Muell.) Broth. J. Bryol. 14: 465--485.
1. Limbella fryei (R. S. Williams) Ochyra, J. Hattori Bot. Lab. 61: 313. 1986
Sciaromium fryei R. S. Williams, Bryologist 35: 52. 1933
Stems 4--8(--13) cm, dark reddish-brown to black, densely matted with dark reddish-brown rhizoids at base, branching irregularly; branches crowded, 1.5--4 cm, usually arising in clusters from adjacent stem segments. Stem leaves 1.5--3.5 x 1 mm; distal laminal cells quadrate to oblong, 7--36 x 5--18 /um; basal cells mostly oblong, 7--40 x 5--14 /um. Branch leaves spreading 50--60, serrate in distal 1/3, 1.5--3.8 x 1--2 mm; distal laminal cells 3--32 x 3--14 /um; basal cells 7--50(60) x 3--14 /um; leaves on flagelliform branches wide-spreading to squarrose, limbidia absent or poorly developed, 0.4--0.8 x 0.1--0.3 mm. Perichaetial leaves acuminate to subulate, squarrose, serrate or serrulate to base, 1.5--2.5 x 0.8--1 mm. Sporophytes unknown.
Perichaetia produced winter to early spring. Mucky peat, decayed wood and bark, coastal shrub swamps; 0--10 m elev.; very rare; Oreg.
The multistratose and serrate margins, lack of paraphyllia, usual dendroid habit, and organic substrate in wetlands distinguish Limbella fryei. It bears superficial resemblance to Leucolepis acanthoneuron, Pleuroziopsis ruthenica and Climacium dendroides, but none of these have the limbidia characteristic of Limbella. For many years, Limbella fryei was known only from the type locality, a “more or less wet pasture,” since destroyed by housing development. A new population was discovered in 1978 (J. A. Christy 1980). E. Lawton (1971) synonymized L. fryei with the Hawaiian L. tricostata, which differs, however, in a number of important characters.
Christy, J. A. 1980. Rediscovery of Sciaromium tricostatum (Sull.) Mitt. (= Limbella tricostata (Sull.) Bartr.) in North America. Bryologist 83: 521--523.
Churchill, S. P. 1986. A revision of Echinodium Jur. (Echinodiaceae: Hypnobryales). J. Bryol. 14: 117--133.
Lawton, E. 1971. Moss Flora of the Pacific Northwest. Nichinan.