Jennings: Manual of Mosses — 15. Mniaceae 137 



J. Leaf broadly obovate, ajjex bluntly rounded, abruptly apiculate or cuspidate; teeth 



blunt 6. M. Tostratum 



J. Leaf apex more or less acute and cuspidate; teeth sharp 8. M. medium 



K. Leaves lanceolate to elliptic-ovate; costa incomplete, dorsally toothed 1. M. hornum 



K. Leaves oblong-ovate or wider than lanceolate; costa usually complete in upper leaves 



at least L 



L.Costa toothed dorsally M 



L.Costa not toothed dorsally N 



M. Cells not collenchymatous, about .014-. 020 mm 2. M. orthorrhynchum 



M. Cells follenchyamtous, about .020-. 030 mm in diameter M. lycopodioides* 



N. Cells rounded and strongly collenchymatous 3. M. serratum 



N. Cells angled and not collenchymatous 4. M. spinulosum 



O. Cells thin-walled, hexagonal, not collenchymatous 5. M. Drummondii 



O. Cells somewhat incrassate, round-hexagonal, collenchymatous 7. M. ciispidatum 



1. Mnium hornum Linnaeus, Hedwig 



(Astrophyllum hornum Lmdberg) 

 Plate LXV 



A robust species in dense tufts, up to 6 or 8 mm high with, erect un- 

 branched stems and terminal rosettes of leaves which reach a length of 3-5 mm 

 but are narrowly elliptic-lanceolate to elliptic-ovate, acute, sharply apiculate, 

 all leaves with a reddish, thickened border, sharply doubly spinosely serrate in 

 the upper half; the costa ending below the apex and spinose dorsally above; 

 leaf-cells angular, not very regularly seriate, rather small: seta solitary, 2-3 cm 

 long; capsule subpendulous, finally horizontal, ovate- elliptic and tapering to a 

 distinct neck, when old pale yellowish with a red mouth; operculum conic- 

 apiculate: dicicous, the antheridial flowers being disc-like. The leaves are 

 proportionally narrower than the other species of the genus and the calyptra 

 often remains for a tim.e clasping the seta just below the capsule, mature in 

 late spring or summer. 



On shaded soil and rocks and banks of streams: Europe, Algeria, Japan, 

 North America from Newfoundland to Georgia and west to Ohio and Ten- 

 nessee. (Lesquereux and James in their manual say: "More generally on 

 quartz or schistose rocks.") but in our region usually among rocks on sand 

 where often subject to flooding. 



Fairly common in the mountains of Pennsylvania » especially in the Ohio Pyle region 

 of Fayette County, on sandy soil along the river. Now known from Bedford, Cambria 

 (Porter), Clarion, Clearfield, Elk, Fayette, Forest, Somerset, Venango, Warren, and 

 Westmoreland counties. Specimen figured: One mile up Meadow Run, Ohio Pyle. June 

 23, 1940. Chas. M. Boardman. 



2. Mnium orthorrhynchum Bridel 



(Astrophyllum orthorrhynchum Lindberg) 



Quite similar to M. serratum but the leaf-cells only about .01 5-. 020 mm; 

 densely tufted; leaves close, oblong-ovate, doubly spinose-serrate from below 

 the middle- costa usually ending in the apiculation, toothed dorsally above; leaf- 



* Mnium lycopodiaides (Hooker) Schwaegrichen, as reported from Blair and Elk 

 counties in our region (Porter's Catalogue), has the stem winged with decurrent leaf- 

 bases; strong reddish, dorsally toothed costa; cells hexagonal and de?.nitely collenchyma- 

 tous. Eurasia, and rather rare in the northernmost United States. 



