Jennings: Manual of Mosses — 31. Hypnaceae 223 



7. Amblystegium riparium [Linnaeus] Bryologia Europaea 



(Hypnum riparium Linnaeus; H. laxi folium Bridel; Stereodon 

 riparium Mitten; Leptodictyum riparium Warnstorf) 



Plate XLII 



Loosely cespitose, yellowish-green, the flat tufts soft: stems creeping, sub- 

 pinnate, the branches usually 2 or 3 cm long, spreading to horizontal, the 

 stems sometimes floating and reaching a length of 8 or 10 cm; stem-leaves 

 2-4 mm long, rather widely spreading or almost squarrose both wet and dry, 

 often somewhat complanate, at tips of branches more or less secund, widely 

 lance-ovate to oblong-lanceolate, gradually tapering to a fine, flat, non-chan- 

 neled acumination, shortly decurrent, rounded at base, non-auriculate, some- 

 what excavate; branch-leaves similar but smaller, all leaves entire and plane- 

 margined; costa fairly strong, reaching from one-half to three-fourths the 

 length of the leaf; median leaf-cells linear-rhomboid, prosenchymatous, usual- 

 ly 8-12(-15):l, thin-walled, chlorophyllose, towards the base lax and sub- 

 rectangular, at the angles often somewhat larger, rectangular, and sub-inflated, 

 but not forming very distinct nor hyaline patches: seta usually 1-2 cm long; 

 capsule rather turgid, oblong-cyilndnc, arcuate, inclined; peristome hypnoiJ 

 but relatively rather large; teeth dark orange, cilia 2 or 3, appendiculate, about 

 as long as the entire or slightly parted segments, the basal membrane :-each- 

 ing to about two-fifths as high as the peristome; annulus 2-3-seriate; exothecial 

 cells very much smaller at rim, below becoming irregular to rectangular, 

 medium-walled; spores minutely roughened, .Oil-. 014 mm, mature in spring: 

 autoicous. 



In swamps, springs, brooks, etc., on bases of trees, roots, stones, etc., 

 sometimes floating; almost cosmopolitan; in North America ranging from the 

 Arctic regions to Louisiana and Cuba. 



Probably common in our region, in suitable habitats. Now known from Allegheny, 

 Beaver, Butler, Centre, Crawford, Erie, Indiana, and Lawrence counties. Figured from 

 specimen collected at Beaver Falls, Beaver Co., O.E.J. , May 14, 1907. 



The specimen from Centre Co., in swampy spot in gap of Bald Eagle Mt., 

 near Matternville, O.E.J., Sept. 20, 1909, has slenderly acuminate leaves 

 approaching longijolium (Schultz) Bryologia Europaea. 



7a. Amblystegium riparium var. flaccidum (Lesquereux and 



James) Renauld and Cardot 



Plate XLII 



Smaller ?.nd of a much more slender habit; leaves more distant and tend- 

 ing to narrowly lanceolate and slenderly acuminate. 



McKean Co.: East Branch swamp, near Bradford, June 15, 1895. D.A.B. (figured). 



2. Amblystegiella Loeske 

 Autoicous or dioicous: very slender, stems filiform, mostly creeping, irregu- 

 larly branched; leaves rather laxly disposed, erect-spreading or rarely weakly 

 secund, lanceolate to lance-subulate from a sometimes somewhat decurrent 



