Jennings: Manual of Mosses — 5. Pottiaceae 85 



well developed, upwards cylindrical, rarely excurrent; leaf-cells small, rounded- 

 quadrangular, often smooth, sometimes the basal elongate and pellucid: seta 

 long, erect; capsule erect, oblong to cylindric, sometimes slightly arcuate, 

 short-necked, smooth; no annulus; peristome inserted on the edge of the urn, 

 papillose, the trabeculae projecting; teeth 16, plane, narrow, undivided, or 

 perforate, or cleft to the base into filiform parts approximate in pairs; spores 

 small; operculum conic-rostrate; calyptra smooth. 



A widely distributed genus of 90 species, on soil or rock, mainly in tem- 

 perate regions; 17 species in North America; only one in our region. 



1. DiDYMODON RECURViROSTRis [Hedwig] Jennings 



(D. rubellus Bryologia Europaea; Barbula rubellct Mitten; 

 Weisict recurvirostra Hedwig) 



Cespitose in large, soft patches, bright green above, rusty red below; stems 

 erect, branched, usually 2-5 cm high, radiculose below; leaves when dry flexu- 

 ous and somewhat curled, when moist somewhat recurved-spreading from the 

 appressed and whitish base, narrowly lance-linear, the comal longer, abruptly 

 acute, margin narrowly revolute to near apex, apex obscurely denticulate; costa 

 either ending in the apex or minutely apiculate-excurrent; basal leaf-cells 

 elongate, rectangular, pellucid, medium-walled, the median and upper much 

 smaller, papillose, rather obscure, quadrate; perichaetial bracts long-sheathing: 

 seta long, red, slender, sinistrorse; capsule erect, oblong-cylindric, becoming 

 reddish-brown, smooth; annulus fragile, revoluble; peristome-teeth 16, united 

 at base into a very low membrance, linear from a wider base, nodose-articulate, 

 reddish, minutely roughened, with the median line but rarely divided; lid 

 short, obliquely conic-rostrate; spores mature in summer or in early autumn: 

 paroicous or synoicous. 



On wet, usually calcareous rocks, stones, walls, etc., widely distributed in 

 the Old World and, in North America, occurring from Greenland to Alaska 

 and south to the northern United States. Although not yet recorded from 

 our region this species is to be expected here. 



8. Barbula Hedwig 



Dioicous; paraphyses filiform: more or less slender and densely and deeply 

 cespitose, the tufts green to brownish: stems with central strand, thickly- 

 leaved, forked; leaves erect-spreading, rarely recurved-squarrose, keeled, oblong 

 to prolonged linear-lanceolate; with mostly revolute margins; costa strong, 

 ending in the point, or excurrent; leaf-cells very small, thickened and opaque, 

 papillose both sides; basal leaf-cells enlarged, quadrate to rectangular, colored: 

 seta long, erect; capsule erect, rarely a little inclined, oblong to cylindric, 

 straight or rarely a little arcuate; annulus distinct or none; peristome rarely 

 rudimentary, or none; the teeth united below into a rather low basal membrane 

 which is rather deeply inserted, the 32 teeth spirally one to several times dex- 

 trorsely wound, filiform; operculum conic-rostrate; calyptra cucullate, long- 

 rostrate, reaching to about the middle of the urn; spores small. 



