80 American Midland Naturalist Monograph No. 6 



of the capsule; spores orange-pellucid, papillose, about .016-.019 mm in 

 diameter, mature in spring. 



Almost cosmopolitan on bare earth in fields, excavations, along road- 

 sides, etc. 



Allegheny Co.: On shale cliffs, Little Sewickley Creek, 2 mi. n. of Edgeworth, 

 C.M.B. Bedford Co.: On shale cliff, Gravel Pit Sta. C.M.B. June 15, 1941. Fayette 

 Co.: Ohio Pyle, on clay bank, September 1-3, 1906. O.E.J, and G.K.J, (figured.) 

 McKean Co.: Bradford, Nov. 21, 1896, Divide, Bolivar and Bennett, Dec. 15, 1896, 

 and Quintuple, Mar. 20, 1898. D.A.B. Washington Co.: Linn and Simonton. (Por- 

 ter's Catalogue). Westmoreland Co.: Clay bank, Darlington, C.M.B. May 19, 1945. 



3. Gymnostomum Hedwig 



Dioicous: densely cespitose, rusty in color below: stem thickly foliate, 

 sparsely radiculose, in cross-section circular, the central strand few-celled, the 

 branching dichotomous; leaves erect-spreading, more or less carinate, not 

 crisped but when dry, more or less appressed and curved; elongate-lanceolate 

 or subulate to sub-lingulate, margin plane; costa strong, vanishing below the 

 apex; upper leaf- cells rounded-quadrate, small, thickly papillose on both sides, 

 as is also the costa, lower cells rectangular, the walls yellow to hyaline; peri- 

 chaetial leaves somewhat sheathing at the base; seta long, erect; capsule erect, 

 symmetric, oval or oblong, when ripe smooth and shining, the wall of the 

 capsule not distinctly thickened at the mouth; peristome none; operculum 

 conic, long rostrate, easily deciduous; calyptra narrowly cucullate, covering 

 about half of the urn. 



A widely distributed genus of II species, mainly occurring on calcareous 

 rocks; 3 species occurring in North America; two in our region. 



Key to the Species 



a. Stems usually less than 2 cm; at least some of the leaves obtuse, narrowly lingulate 



to ligulate 1. G. calcareum 



A. Stems from 1 to 10 cm; leaves oblong to linear-lanceolate, more or less acute 



2. G. aeruginosum 



1. Gymnostomum calcareum Nees and Hornschuch 



(G. viridulum Bryol. Eur.; G. tenue of L. and J. Manual) 

 Plate XVI 



Densely cespitose, yellowish-green: stems erect, branched, up to 10 mm 

 high; leaves about I mm long, spreading, somewhat recurved, elongate-oblong- 

 lanceolate, somewhat concave, usually larger and tufted at the apex of the 

 stem, obtuse, plane-margined; upper leaf-cells densely papillose, small, incras- 

 sate, obscure, the interior basal cells hyaline, rectangular or up to 2-3:1; costa 

 strong, ending below the apex: seta erect; capsule oblong, often somewhat con- 

 stricted below the mouth when dry and empty, erect, symmetric, tapering 

 below; lid conic, obliquely rostrate, the beak one-half to two-thirds as long as 

 the urn; calyptra cucullate; annulus none; peristome none; exothecial cells 

 rectangular to quadrate, at the mouth becoming smaller, darker and quadrate 

 in 3 to 5 rows; spores smooth, .008-.0I1 mm in diameter, mature in summer. 



