THE BRYOLOGIST 
Vol. XXI 
May, 1918 
7 f, 
, V 
* 12 1918 
ft a/ Wluse^' 
No. 3 
ILLUSTRATED KEY TO THE WESTERN SPHAGNACEAE 1 
T. C. Frye 
SPHAGNUM, Peat Moss 
Plants grayish when dry. Branches usually tufted. Leaves veinless. 
Leaf-cells of 2 quite different kinds, the large hyaline ones with spiral or ring- 
like thickenings in their walls, the narrow long green ones alternating with the 
hyaline ones and so narrow that they might be mistaken for the walls of the 
hyaline ones. Calyptra irregularly torn. Capsule elevated by a false stalk 
which is a modified branch. Lid deciduous. Peristome none. Plants of un- 
drained bogs; or on high mountains and in cool regions growing in damp places 
in almost any situation. (Gk. sphagnos, some kind of moss.) 
Key and Comparison of Species 
A. Cortical cells of the stems and branches with spiral thickenings (see PI. XVII, 
fig. 2). Group i 
AA. Cortical cells of the stems and branches without spiral thickenings (see PI. 
XIX, fig. 1). 
B. Branches in tufts of 6-12. Group 2 
BB. Branches in tufts of 1-6. 
C. Green cells of the branch-leaves in cross section not exposed on either 
surface, the cell-cavity elliptic (see PI. XVIII, fig. 12). Group 2 
CC. Green cells of the branch leaves in cross section exposed exclusively or 
more broadly on the outer side (see PI. XVIII, fig. 14), or if with cen- 
tral cell-cavity and about equal exposure on the 2 sides (see PI. XIX, 
fig. 8) then the plants brownish-green rather than reddish-green. 
D. Stem-leaves not fimbriate nor lacerate, small, pointed (PI. XIX, fig. 
3). Group 2 
DD. Stem-leaves fimbriate or lacerate, large or small, pointed to rounded 
(see PI. XX, fig. 5). Group 3 
CCC. Green cells of the branch-leaves in cross section exposed exclusively 
or more broadly on the inner side (PI. XXII, fig. 13), or if with central 
cell-cavity and about equal exposure on the 2 sides (PI. XXI, fig. 9) 
then the plants reddish-green rather than brownish-green. Group 4 
1 The arrangement and condensed nature of this paper prevents acknowledgment to various 
authors whose works have been found useful, except perhaps the most admirable treatment of the 
genus by A. L. Andrews in Flora of North America. 
The March number of the Bryologist was published April 30, 1918. 
