BFNA Title: Hypnaceae
Author: Schofield, Buck & Ireland 
Date: December 15, 2008
Edit Level: R
Version: 1

Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden
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Wilfred B. Schofield †

William R. Buck

Robert R. Ireland


Plants small to robust, forming lax to dense wefts or mats, creeping, suberect, or erect, dark to yellow-green, golden or orange, sometimes reddish brown or nearly black, often lustrous. Stems 0.5--20 cm, branching irregularly to regularly pinnate or 2-pinnate, with or without a 1-stratose hyalodermis, central strand present or absent; pseudoparaphyllia filamentous, foliose or lacking; rhizoids smooth or papillose, often in clusters proximal to juncture of leaves on adaxial surface of stems and branches; axillary hairs with 1--2(--4 ) short, brown basal cells and 1--several elongate, hyaline distal cells. Stem and branch leaves similar or less commonly differentiated, straight to homomallous, often falcate-secund, occasionally complanate or julaceous, typically ovate-lanceolate, often asymmetric, sometimes linear, lanceolate, or triangular, obtuse to acuminate, occasionally plicate, sometimes decurrent; margins entire or toothed, often plane, occasionally recurved proximally or sometimes throughout; costa short and double to obscure or absent; laminal cells mostly linear medially and distally, varying from hexagonal to elongate-sinuose, smooth or distally sometimes prorulose at distal ends on abaxial surface; alar cells usually differentiated, often quadrate to short-rectangular, sometimes enlarged and inflated, colored or similar in color to other cells, excavate or plane. Specialized asexual reproduction sometimes by leafy propagula or filamentous gemmae clustered in leaf axils. Sexual condition autoicous, dioicous, or phyllodioicous. Seta elongate, smooth. Capsule inclined to horizontal, sometimes erect, cylindric or ovoid, usually smooth, often constricted below mouth when dry and empty; operculum conic or rostrate; peristome usually double, exostome teeth 16, cross-striate basally, papillose distally; endostome basal membrane high, rarely low, usually free or sometimes fused to the exostome, segments 16, cilia 1--3, nodose, rarely rudimentary or lacking. Calyptra cucullate, smooth, naked, rarely hairy. Spores spherical to oval, mostly finely papillose, rarely smooth.


Genera 60 (20 in the flora), cosmopolitan, most diverse in subtropics and tropics.


The Hypnaceae is a taxonomically problem-filled family both in the genera included and the species ascribed to various genera. The family once held a high proportion of pleurocarpous species; but as genera are monographed, they are often placed in other families.  The distinctive hypnoid peristome has been used as a significant feature, but this is not entirely reliable.


SELECTED REFERENCES   Buck, W.R. and B. Goffinet.  2000.  Morphology and classification of mosses.  In: A. J. Shaw and B. Goffinet, eds.  Bryophyte Biology.  Pp. 71--123. Cambridge and New York.  Crum, H. A. and L. E. Anderson.  1981.  Mosses of Eastern North America.  Vol. 2.  Pp. 1126--1208.   New York  Lawton, E.  1971.  Moss Flora of the Pacific Northwest.  Nichinan.



l. Stems with a hyalodermis, although sometimes indistinct.

2. Leaf cells covered with granular cuticular papillae on abaxial surface; plants large, yellowish green; leaves undulate.…….……… 2. Buckiella, p. xx

2. Leaf cells lacking granular cuticular papillae; plants smaller; leaves not undulate.

3. Pseudoparaphyllia present, foliose…………………….10. Hypnum (in part), p. xx.

3. Pseudoparaphyllia absent.

4. Leaves entire to minutely serrulate; asexual propagula often present as clusters of  cylindric or fusiform brood bodies of 2--6 smooth cells in leaf axils of stems and branches ..………………………..….…..…11. Isopterygiopsis, p. xx

4. Leaves serrulate to serrate; asexual propagula absent . . . . . 8. Herzogiella, p. xx

1. Stems without a hyalodermis.

5. Leaf cells prominently prorulose on abaxial surface near midleaf.

6. Leaf cells prorulose at both ends; leaves ± straight . 4. Chryso-hypnum, p. xx

6. Leaf cells prorulose only at distal ends; leaves falcate ..... 5. Ctenidium, p. xx

5. Leaf cells smooth or inconspicuously prorulose at leaf apex or base.

7. Basal row of leaf cells with a large prorula at proximal end; plants restricted to California ………… 6. Dacryophyllum, p. xx

7. Basal row of leaf cells smooth; plants distributed otherwise.

8. Leaves with bluntly obtuse to broadly rounded apices, ecostate……………… 1. Bryocrumia, p. xx

8. Leaves acute to acuminate, rarely subobtuse, usually costate.

9. Lateral and dorsal leaves strongly differentiated in shape.

10. Laminal cells thin-walled, at least those of the lateral leaves relatively short ….… 20. Vesicularia, p. xx

10. Laminal cells thick-walled and porose, elongate . .  7. Gollania, p. xx

9. Lateral and dorsal leaves not particularly differentiated.

11.  Branches with brood branchlets at tips ......…. 14. Platygyrium, p. xx

11. Branches without brood branchlets at tips.

12. Apical leaf cells shorter than those at midleaf ………………. 7. Taxiphyllum (in part), p. xx

12. Apical leaf cells as long as or longer than those at midleaf.

[Ed. note: Key shifted to left]

13. Plants with filamentous 1-seriate pseudoparaphyllia, these rarely 2-seriate at base ……..…………12. Isopterygium, p. xx

13. Pseudoparaphyllia foliose or absent.

14. Distal laminal cells ca. 4--6:1; plants mostly on soil, rocks or bases of trees ………………………………… 9. Homomallium, p. xx

14. Distal laminal cells longer; plants on various substrates but if cells somewhat             short then usually epiphytic.

15. Leaves long-triangular, widest at base; alar cells scarcely differentiated; plants mostly Arctic or high elevation … 13. Orthothecium, p. xx

15. Leaves lanceolate to ovate, widest beyond base; alar cells mostly differentiated; plants mostly temperate.

16. Plants robust, plumose, suberect, pinnately branched and forming fronds; leaves strongly plicate ………………16. Ptilium, p. xx

16. Plants medium-sized, if robust, not plumose, prostrate, irregularly branched; leaves smooth, weakly plicate or undulate.

17. Plants with elongate, asexual reproductive bodies in clusters in leaf axils………………..15. Pseudotaxiphyllum, p. xx

17. Plants lacking clustered asexual reproductive bodies.

18. Branches usually strong curled when dry; capsules erect; exostome teeth smooth...17. Pylaisia, p. xx

18. Branches not curled when dry; capsules suberect to curved; exostome teeth mostly cross-striolate.

19. Plants with appressed leaves and often terete branches when dry…………...19. Tripterocladium, p. xx

19. Plants with erect to spreading leaves when dry, often falcate.

20. Plants complanate, leaves sometimes upturned, margins entire; capsules suberect .... 3. Callicladium, p. xx

20. Plants not complanate or if so, leaf margins serrulate to serrate; capsules curved.

21. Stems usually pinnately or irregularly branched, rarely subjulaceous; leaves usually spreading from an erect base..10. Hypnum (in part), p. xx

21. Stems simple or sparingly and irregularly branched, sometimes julaceous or subjulaceous; leaves complanate-foliate ……….. 18. Taxiphyllum (in part), p. xx