10 American Midland Naturalist Monograph No. 6 



Abbreviations and Signs Used in the Manual 



cm Centimeter, equals the one-hundredth part of a meter, or about two-fifths of an inch. 



mm — Millimeter, equals one-tenth of a centimeter; about one-twenty-fifth of an inch. 



C.M.B.— Charles M. Boardman. 



D.A.B.— D. A. Burnett. 



S.K.E. — Sidney K. Eastwood. 



G.K.J. — Grace K. Jennings (Mrs. O. E. Jennings). 



O.E.J. — O. E. Jennings. 



J.A.S.— John A. Shafer. 



- The hyphen used between figures or betA-een words denotes either an intermediate state 

 or a variation from one to the other extreme. 



Analytical Key to the Genera of Mosses 

 OF Western Pennsylvania 



Order I. Sphagnales 



Whitish mosses with fasciculate branches, mostly bog plants; leaf-cells of two kinds, 

 — large hyaline ones separated by narrow chlorophyllose ones; ecostate; opjerculate but 

 with no peristome Sphagnum, p. 20 



Order II. Andreaeales 



Dark colored or blackish, very fragile, alpine or subalpine plants growing in 

 cushions on granitic, hard sandstone, or slaty rocks; either costate or ecostate; leaf- 

 cells small and quite opaque; capsule dehiscing by four longitudinal slits, the valves 

 remaining united at the apex until quite old and empty Andreaea, p. 43 



Order III. Bryales 



Leaves various but not sphagnoid, costate or ecostate; capsule dehiscing irregularly 

 or, more often, by a deciduous operculum, often furnished with a peristome, never 

 four-valved as in Andreaea, plants largely green* I 



H aplohymenium irisle is not known to fruit in the United States. 



I. Sfxjrophyte borne at the apex of the main stem, sometimes appearing lateral by 



the growth of a branch A. (AcROCARPi) p. 44 



I. Sporophyte borne at the ajDex of a usually short lateral branch, or appearing 

 axillary B. (Pleurocarpi) p. 172 



I. Sporophytes on rather vigorous, erect, often dendroid secondary branches which 



rise from a rhizome-like primary stem see Thamnium or Climacium 



A. AcROCARPI 



1. Capsule non-operculate (or lid not readily separating) 2 



1. Capsule operculate 10 



2. Green protonema persistent; plants fruiting in autumn, minute 



Ephemerum, p. 1 13 



2. Green protonema persistent; plants fruiting in spring Acaulon, p. 87 



2. Green protonema not persistent, plants fruiting mainly in spring 3 



* Hookeria acutifolia has leaves 4-5 mm long, drying very thin, soft, fluffy, and pale 

 yellow or whitish. 



