— 6i — 



The group-name Squarrosa seems to have been first used by Schliephacke^ 

 and has persisted mostly with the same content since. My only change is the 

 addition of 5'. Angstrdmii which has been passed from group to group and by 

 Russow with clearer insight made a group by itself: Truncata? The most note- 

 worthy characters of the group Squarrosa are to be found in the stem-leaves and 

 perichaetial leaves as already noted. Its distribution is circumpolar, restricted 

 to the northern hemisphere, the southern limit in North America corresponding 

 roughly with the limit of glaciation. 



ID. Sphagnum Angstrdmii Hartmann, 1858. The similarity of the stem- 

 leaves of this species with those of S. squarrosum and 5. teres will be apparent 

 to anyone from the excellent illustrations of Roth,^ and a careful examination 

 will show that this generally similar effect is accompanied, probably in part 

 conditioned by a similar tendency in the resorption of the membrane of the 

 hyaline cells, these species being unique among Litophloea in showing a great 

 resorption upon the outer surface of the stem-leaves with very little upon the 

 inner. The perichaetial leaves of 5. teres and 6". squarrosum are still more unique 

 among Litophloea in that they show throughout their whole extent the normal 

 network of chlorophyll and hyaline cells with fibrils completely lacking and with 

 general resorption of membrane on the outer surface. A fruiting specimen of 

 S. Angstrdmii from the Sullivant herbarium, loaned me through the kindness 

 of Professor Farlow, showed perichaetial leaves with the two kinds of cells differ- 

 entiated in the upper and middle portions, where the hyaline cells were without 

 fibrils and had their membrane resorbed on the outer surface, corresponding 

 then in this last respect with the other two species. Of course the tendency to 

 uniform narrow cells in the lower part of perichaetial and stem-leaves of 5. 

 Angstrdmii, the different pores and chlorophyll cells of its branch-leaves, and ics 

 different gross appearance indicate that its relationship to the other two species 

 is not an extremely close one, probably not closer for example than that between 

 S. teres and S. Girgensohnii, but that its nearest affinity is with S. teres and S. 

 squarrosum seems indubitable. It is to one familiar with Sphagnum recogniz- 

 able immediately in the field by its generally yellow coloration and the effect 

 produced by its large but relatively short leaves, a gross effect quite intermediate 

 between that of the species of Inophloea and of most species of Acisphagnum, 

 while its coloration and habit is hardly that of Malacosphagnum. If one is tempted 

 to confuse it with Inophloea, which is most likely to be the case, a hand-lens is 

 sufficient to distinguish its broadly truncate leaf-apices from the cucullate ones 

 of Inophloea. It is known in North America from two collections, both mentioned 

 by Warnstorf in his last book:^ Hall Island in Bering Sea, collected by Trelease;^ 

 Yukon, collected by J. M. Macoun; the last at about 64° north latitude, the first 



•'■ Beitrage zur Kenntnis der Sphagna 413. 1865. 



2 Zur Anatomie der Torfmoose 29. 1887. Russow had previously (Beitrage zur Kenntnis 

 der Torfmoose 34.. 1865.) included in Truncata two other species. 

 ^ Die europaischen Torfmoose, pi. IV, fig. 3a; pi. V, figs. la, aa. 

 ^ Pfianzenreich 51 : 139. 1911. 



^ Cf. Harriman Alaska Series of the Smithsonian Institution, V, 332. 1910. 



