BARNES — NORTH AMERICAN MOSSES. 



18t 



II. Cells of the exothecium prosenchymatous; seta often yellowy 

 casta usually broad and indistinct below. 



A. Seta red. 



Leaves from a sheathing base, squarrose 

 Leaves not sheathing nor squarrose. 



Mostly erect, capsule cernuous 



Secund, capsule erect . . • . 



D. crispa, 64. 



D. subulata, 66. 

 D. curvata, 67. 



B. Seta yellowish. 



Capsule symmetric, erect 

 Capsule cernuous. 



Strumose 



Not strumose 



D. Fitzgeraldi, 60. 



D. cerviculata, 65. 

 D. heteromalla, 66. 



DICRANUM, p. 67.1 



In this genus the structure of the costa is of diagnostic value. It is 

 either composed of similar cells {homogeneous), or composed of large 

 parenchyma cells and small sclerenchyma cells {stereids). The large pa- 

 renchyma cells {guides = ''Deuter" of Lorentz«) form a row (seldom double) 

 in the middle of the costa touching each other tangentially. They are 

 comparatively large, but little thickened and either empty or starch-bear- 

 ing. ^ 



Monoicous, stems radiculose only at base, costa long excurrent, 



homogeneous. 



D. hyperboreum,* 64. 

 D. fulTellum, 68. 



Capsule erect, not strumose. 

 Striate and furrowed when dry 

 Neither striate nor furrowed when dry 

 Capsule cernuous, strumose. 

 Leaf cells not papillose, capsule oblong-cylindric D. Starkii, 68. 



Leaf cells with papillae over partitions, capsule short-ovate. 



Leaves falcate-secund D. falcatum,^ 68. 



Leaves spreading ...... D. Blytii, 68. 



1 Arranged by Dk. Rodney H. Tkije. 

 ^Pringsheim's Jahrb. f. wissensch. Bot. 6: 374. 

 3 Limpricht: Die Laubmoose 23. 

 •• See Appendix, no. 65. 

 ^ See Appendix, no. 65a. 



