Jennings: Manual of Mosses — 31. Hypnaceae 219 



below; inner peristome yellowish, basal membrane high; segments carinate, 



entire, or slightly gaping along the keel; cilia complete, nodose, rarely appen- 



diculate; lid conic, obtuse to acute; spores small. 



A genus of about 50 species occurring mainly in temperate regions, on 



various sub-strata; about 20 species in North America; at least five in our 



range. 



Key to the Species 



A. Leaves erect-spreading (widely spreading in A. Juratzkinum); median leaf-cells 



about 2-6:! B 



A. Leaves mostly loosely and widely to squarrosely spreading; median leaf-cells mostly 



4-8:1, rarely 10-15:1 F 



B. Cells in middle of leaf about 2-4:1 C 



B. Cells in middle of leaf about 4-6(-8):l B 



c. Very slender; costa thin, ending near the middle of the leaf I. A. serpens 



C. Less slender; costa stronger, almost reaching ap>ex D 



D. Stem-leaves ovate-acuminate, acute, slenderly acuminate; entire or nearly so G 



D. Stem-leaves ovate-cordate, abruptly narrowed to a rather blunt acumination 



3. A. OTthocladon 



E. Costa reaching to about three-fourths the length of the leaf 4. A. ]uratzkanum 



E.Costa reaching about to the middle of the leaf Campyliutn mdicale, p. 2°' I 



F. Slender: median leaf-cells prosenchymatous, hexagonal to hnear, 4-8(-10):l 



6. A. Kochii 



F. Rather robust: median leaf-cells elongate-prosenchymatous to linear, 5-10(-15):l; 



leaves very slenderly acuminate 7. A. nparium 



G.Costa reaching apex or almost so; median leaf-cells averaging about 3:1 



2. A. varium 



G. Costa a little shorter; median leaf-cells averaging about 4:1 5. A. trichopodium 



Amblystegium serpens [Linnaeus] Bryologia Europaea 



(Hypnum serpens Linnaeus) 



Plate XLI 



Dull, more or less yellowish-green, very small and slender, forming thin, 

 soft, densely interwoven mats: stems prostrate, radiculose, irregularly branch- 

 ing, the branches ascending or spreading or erect; leaves rather crowded, when 

 moist variously spreading, when dry more or less appressed and imbricate; 

 stem-leaves lance-ovate to ovate-acuminate, usually long-acuminate, the largest 

 about 0.8-1.0x0.4-0.5 mm, often much smaller, narrowed and decurrent at 

 base, denticulate or entire, somewhat concave, the margins plane; costa usually 

 reaching about to the middle of the leaf or above, often quite faint and indis- 

 tinct; branch-leaves similar but smaller and narrower, usually more lanceolate; 

 median leaf-cells oblong- to rhomboid-hexagonal, about 2-4:1, the basal 

 broader and more rectangular, the alar quadrate to transversely elongate but 

 not forming a well-defined group, some of the apical considerably longer; peri- 

 chaetial leaves lanceolate, thin, plicate, up to 1.5 mm long: seta rather slender, 

 1-3 cm long, reddish, dextrorse; capsule cylindric, the urn below 1.5 mm long, 

 strongly curved, cemuous, constricted below the mouth when dry; lid convex- 

 conic, rather obtusely apiculate; peristome rather large for the capsule, typical- 

 ly hypnaceous, teeth pale castaneous, strongly trabeculate, below dorsally 

 cross-striolate, the dorsal lamellae projecting to form a more or less crenate 



