22 American Midland Naturalist Monograph No. 6 



N. Cuticular cells of stem one-stratose P 



O. Stem-leaves small, not more than 1 mm long, fibrtUose only towards the apex; 



branch-leaves secund 12. S. contortum 



O. Stem-leaves large, 1.5-2 mm long, fibrillose to the base or nearly so; branch-leaves 



not secund 13. S. platyphyllum 



P. Stem-leaves with the hyaline border strongly widened below, fibrils none or only 



in the upp)er cells 15. S. subsecundum 



p. Stem-leaves with a uniformly wide border and with fibrils more numerous Q 



Q. Stem-leaves strongly auriculate, large, 1.5-2 mm long, fibrillose in the upper two- 

 thirds at least, or clear to the base 14. S. auriculatum 



Q'. Stem-leaves not or but slightly auriculate at the base, usually of medium size, fibril- 

 lose in about the upjaer two-thirds R 



R. Stem-leaves about 1-1.5 mm long, with the hyaline cells septate, and m the upper 



half fibrillose 16. S. inundatum 



R. Stem-leaves 1.3-1.5 (-2) mm long, very little septate, fibrillose in the upper two- 

 thirds, or to the middle 17. S. pungens 



S. Stem-leaves erose or lacerate-fimbriate at the broadly rounded ap>ex, non-fibrillose T 



S. Stem-leaves not fimbriate, but truncate or toothed at the ap)ex, usually more or less 



fibrillose, at least above U 



T. Stem-leaves spatulate, fringed at the ap>ex and around the upper half; plants deli- 

 cate, with slender branches and never' red 18. S. fimbrijtum 



T. Stem-leaves lingulate, fringed only at the very broad apex; branches thicker than 



in 5. fimbriatum 19. S. Ghgensohnii 



V. Stem-leaves lingulate V 



U. Stem-leaves more or less equilaterally triangular or triangular-lingulate W 



V. Pigment red, never brown (green in var. ) 20. S. Warnstorfii 



V. Pigment brown 21. S. fuscum 



w. Branch-leaves five-seriate, when dry not lustrous 22. S. qititiqucfarium 



w. Branch-leaves not distinctly 5seriate, when dry more or less lustrous X 



X. Stem-leaves usually non-fibrillose and non-porose; branch-leaves usually lustrous 



when dry 23. S. plumulosum 



X. Stem-leaves usually fibrillose and porose; branch-leaves usually not glossy when 



dry 24. S. acutifolium 



Section I. Inophloea 



Cuticular cells of stems and branches reinforced with spiral fibers and 

 porose. 



Subsection I. Cymbifolia 



Large, with the branch-leaves boat-shaped, cucullate and scabrous at the 

 back of the apex. Stem-leaves not bordered. 



1. Sphagnum imbricatum (Homschuch) Russow 



(S. Austini Sullivant) 

 Plate I 



This species occurs in bogs and wet moors in Europe and Asia and in 

 North America from Labrador to Alaska and south to Louisiana. In our 

 region it is represented by the following variety. The typical form, as com- 

 pared with the following variety, has usually more yellowish or brownish 

 denser tufts with the shorter comal branches more erect and the divergent 

 branches more densely-leaved and more ascending; while the hyaline cells of 

 the stem-leaves are sparsely comb-fibrillose on the inside face of the lateral 

 walls; otherwise the characters of variety and species are identical; in fact it 



