Jennings: Manual of Mosses — I. Sphagnales 21 



B. Cuticular cells of stem and branches not fibrose G 



c. Chlorophyllose cells of branch-leaves in cross-section exposed eithett dorsally or ven- 



trally, or both D 



c. Chlorophyllose cells of' branch-leaves centrally placed and entirely enclosed by the 



hyaline cells 5. S. magellamcum 



D. Lateral walls of chlorophyllose cells of branch-leaves facing into the hyaline cells 



either more or less papillose or with comb-fibrils --E 



D. Lateral walls of the chlorophyllose cells smooth F 



E. Chlorophyllose cells of branch-leaves in cross-section more or less equilaterally tri- 

 angular and exposed only on the ventral (inner) side of the leaf or, in the upper 

 part of the leaf, usually broadly trap>ezotdal and exposed on both sides, and, 

 mainly in the lower part of the leaf, the walls facing into the hyalinf cells with 



comb-fibrils 1. S. tmbrtcatum 



E. Chlorophyllose cells of branch-leaves in cross-section narrowly to broadly spindle- 

 shaped or barrel-shaped, usually with thickened outer walls narrowly free on both 

 surfaces or nearly enclosed, the walls facing into the hyaline cells mostly minutely 



papillose 2. S. papillosum 



F. Chlorophyllose cells of branch-lea\es in cross-section very broadly triangular or 



triangularly trapezoidal, and v.ith the broader face ventral 3. S. affine 



F. Chlorophyllose cells narrowly triangular or trapezoidal, seen in cross-section not 



more than one-half as wide as long, usually less 4. S. palustre 



G. Chlorophyllose cells of branch-leaves in cross-section elliptical or more or less barrel- 

 shaped or rectangular, but not triangular or trapezoidal H 



G. Chlorophyllose cells in cross-section triangular or trapezoidal with one or both faces 



free I 



H. Hyaline cells of stem-leaves non-fibrillose; chlorophyllose cells of branch-leaves in 

 cross-section enclosed on both surfaces, with the lumen sub-central, elliptic; 

 branch-leaves squarrose in their upper half; cuticular cells of branches with an 



apical pore 7. S. compactum 



H. Hyaline cells of stem-leaves fibrillose; chlorophyllose cells of branch-leaves free 



on both surfaces, their hyaline cells with numerous pores N. (Subsecunda) 



I. Face of chlorophyllose cells of branch-leaves in cross-section dorsally free; hyaline 

 cells strongly convex ventrally the walls adjoining the chlorophyllose cells smooth 



or papillose J 



I. Face of chlorophyllose cells free on the ventral (inner) surface of the leaf, the hya- 

 line cells dorsally strongly convex, the inner walls adjoining the chlorophyllose 



cells smooth S. (Acut, folia) 



J. Hyaline cells of median dorsal surface of branch-leaves with about 5 very large 

 pores, but these smaller towards the leaf-apex; chlorophyllose cells with the 



exterior walls strongly thickened K. (Squarrofa) 



J. Hyaline cells with pores on median leaf-surface (dorsal) none or very few; 



chlorophyllose cells with the walls not strongly thickened L (Cuspidata) 



K. Stem-leaves with a rounded hut narrow apex; branch-leaves at least 2 mm long 



8. S. squaTTOSum 



K. Stem-leaves not narrowed but rounded at apex; branch-leaves less than 1.8 mm long 



9. S. teres 



L. Cortical cells of stem small and thick-walled not much different from the inner 



cells M 



L. Cortical cells of stem distinctly larger in 1-3 layers, thin-walled 



1 \. S. cuspida:um 



M. Branch-leaves 1-2 mm long, when dry undulate and with more or less recurved tips 

 and with the dorsal pores of the hyaline cells more or less restricted to the cell- 

 angles 10. S. recur yum 



M. Branch-leaves when dry but weakly undulate, scarcely recurved, about 1 mm long, 



the upper hyaline cells with pores both in the cell-angles and along the sides 



ICb. S. recurv. var. tenue 



N. Cuticular cells of stem 2-3-stratose O 



