OF WESTERiV PENNSYLVANIA 159 



costate. 10. M. punctatum. 



f. In swamps; leaves not usually apiculate and costa not usually 

 reaching apex; often very large. 10. M. punct. var. elatum. 



g. Leaves serrate with a single row of teeth, h. 

 g. Leaves serrate with a double row of teeth. 



k. 

 h. Leaves serrate only in upper two-thirds. 



6. M. cuspidatuin. 

 h. Leaves serrate to the base or very nearly so. 



i. 

 f. Teeth slender and usually of 2-4 cells. 8. M. affine var. ciliare. 



i. Teeth usually of but one cell and not so slender. 



. J- 

 j. Leaf apex bluntly rounded, abruptly apiculate. 



S. M. rostratum. . 

 j. Leaf apex more or less acute and cuspidate. 



7. M. medium. 

 k. Leaves lanceolate; costa incomplete, dorsally toothed. 



1. M. hornum. 



k. Leaves wider than lanceolate; costa usually complete in upper 



leaves at least. 1. 



1. Costa toothed dorsally. m. 



1. Costa not toothed dorsally. n. 



ni. Cells not coUenchymatous, about .014-.018 mm. 



2. M. orthorrhynchum. 

 m. Cells coUenchymatous, about .02O-.030 mm. in diameter. 



M. lycopodioides* 

 n. Cells rounded and strongly coUenchymatous. 



3. M. serratum. 

 n. Cells angled and not coUenchymatous. 4. M. spinulosum. 



1. Mnium hornum Linnseus, Hedwig. 

 (Astrophylhiiu hornuut Lindberg). 



A robust species in dense tufts, with erect unbranched 

 stems and terminal rosettes of leaves which reach a length of 

 3-5 mm. but are oblong- to narrowly elliptic-lanceolate, 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 

 incrassate, angular, not very regularly seriate, rather small : 

 seta solitary, long; capsule subpendulous, finally horizontal, 

 ovate-elliptic and tapering to a distinct neck, when old pale 

 yellowish with a red mouth; operculum conic-apiculate : 

 dioicous, the antheridial flowers being disc-like. The leaves 

 are proportionally narrower than the other species of the 

 i^enus and the calyptra often remains for a time clasping the 

 seta just below the capsule, mature in April to May. 



In shaded, swampy or springy places and banks of streams : 

 Europe, Algeria, Japan, North America from Newfoundland 



'■Miiinin lycopodioides (Hooker) Schwaegrichen, as reported from 

 Blair and Elk Counties in our region (Porter's Catalogue), is probably, 

 synonymous with Mniuiii pseudo-lycopodioides C. Mueller and Kindberg, 

 which appears to be hardy separable from Mnium orthorrhynchum (Bridel) 

 Bryologia Europaea. 



