BFNA Title: Leptodontaceae
Author: L. R. Stark 
Date: June 3, 2008
Edit Level: R 
Version: 1

Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden

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Lloyd R. Stark

Plants epiphytic, small to medium in size, light to yellow-green, with creeping primary stems bearing arcuate to erect branches. Stems irregularly pinnately branched, the branches incurved or rigid when dry and produced in clusters of 1--5 on either side of a vegetative growth interval; paraphyllia present or absent; pseudoparaphyllia subfoliose to nearly filamentous, entire; axillary hairs 6--8 per axil, of 1--2 short proximal cells with brownish walls and 2--4 elongate hyaline distal cells. Branches short to elongate, simple to much-branched. Leaves spirally inserted, loosely appressed to imbricate, erect spreading to nearly squarrose when moist, rapidly spreading when moistened, mostly ovate-lanceolate, margins entire or serrate distally, apex acute to shortly acuminate; costa single and ending before leaf apex or short and double; medial cells isodiametric to linear, smooth; alar cells quadrate to transversely elongate. Sexual condition autoicous or dioicous. Perigonia gemmiform, lateral. Perichaetia larger, lateral, with elongating paraphyses and inner perichaetial leaves following fertilization. Specialized asexual reproduction absent. Seta single, 1--4 mm in length. Capsule immersed to emergent, erect, cylindrical, symmetric, stomates absent or basal and sunken; annulus absent; operculum conic-rostrate; peristome mostly double, pale; exostome of 16 teeth; endostome rudimentary or absent to well developed, cilia absent. Calyptra cucullate, hairy. Spores spheric, minutely papillose.

Genera 5--6, species ca. 20--30 (3 genera, 4 species in the flora): worldwide, primarily temperate regions.

The family Leptodontaceae is defined by the combination of epiphytic habit, branching pattern of clusters of branches alternate with unbranched intervals bearing inflorescences, “double” sporophytic phenological cycle in which two cohorts of sporophytes mature simultaneously with embryos overwintering, subfoliose pseudoparaphyllia, cucullate calyptrae, sheathing postfertilization perichaetial leaves, central strands lacking in shoots, shortened setae, no annuli, and a hydrocastique exostome that flexes open when wet and flexes inward when dry, thus serving to disperse spores during wet periods.  The Leptodontaceae as treated here comprise only Forsstroemia, Leptodon, and Alsia. Recently described or relocated genera in the family include Taiwanobryum, Cryptoleptodon, and Caduciella (J. Enroth 1991, 1992, 1993).  Molecular evidence indicates that this small family may not be monophyletic, and is better viewed within the larger context of the family Neckeraceae (e.g., S. Maeda et al. 2000; M. S. Ignatov et al. 2007).

SELECTED REFERENCES  Enroth, J. 1992. Corrections to Cryptoleptodon, Forrstroemia and Leptodon (Leptodontaceae, Musci). Journal of the Hattori Botanical Laboratory 71: 75--82. Maeda, S., K. Kosuge, D. Gonzalez, E. De Luna, and H. Akiyama. 2000. Molecular phylogeny of the suborder Leucodontineae (Musci; Leucodontales) inferred from rbcL sequence data. Journal of Plant Research 113: 29--38. Stark, L. R. 1987. A taxonomic monograph of Forsstroemia Lindb. (Bryopsida: Leptodontaceae). Journal of the Hattori Botanical Laboratory 63: 133--218. Ignatov, M. S., A. A. Gardiner, V. K. Bobrova, I. A. Milyutina, S. Huttunen, and A. V. Troitsky. 2007. On the relationships of mosses of the order Hypnales, with special reference to taxa traditionally classified in the Leskeaceae. In: A. E. Newton and R. S. Tangney, eds. 2007. Pleurocarpous mosses, systematics and evolution. Boca Raton. Pp. 177--213. Buck, W. R. and  B. Goffinet. 2000. Morphology and classification of mosses. In: A. J. Shaw and B. Goffinet, eds. 2007. Bryophyte Biology. Cambridge. Pp. 71--123.


1. Paraphyllia absent . . . . 1. Forsstroemia, p. XX.

1. Paraphyllia present.

2. Secondary stems flagelliform, [calyptra hairy, endostome rudimentary,] rare (Colorado)  . . . . 2. Leptodon, p. XX.

2. Secondary stems not flagelliform, calyptra smooth, endostome well developed, common in Pacific Northwest  . . . . 3. Alsia, p. XX.