ORDER I. SPHAGNALES 



Family i. SPHAGNACEAE. The Peat Mosses 



The Peat Mosses are so different from the other mosses that 

 many bryologists do not consider them as mosses at all, but 

 would put them in a separate class. Their protonema is much 

 like the prothallium of a fern, and the stalk upon which the cap- 

 sule is borne is- not at all homologous with the seta of the other 

 mosses, as it is an outgrowth from the gametophyte and not the 

 lower portion of the sporophyte, i. e., it is developed from the 

 moss plant instead of from the fertilized egg-cell. The capsules 

 are globose with a well marked operculum but no peristome. 

 The structure of the leaves is also very different from that 

 of the other mosses. The cells of the branch leaves are of two 

 sorts, very large hyaline rhomboidal or elliptical cells with 

 the walls spirally thickened and often perforated by round 

 pores, and the true chlorophyllose cells, which are narrow and 

 elongated and lie between the others. While most forms are 

 grayish green the leaves of some species are pink or deep red and 

 furnish microscopic mounts of very great beauty. 



Although the Sphagnaceae consist of but one genus, the num- 

 ber of species is very large and the distinctions are very puzzling. 

 They all grow in bogs, swamps, moist mountain summits, etc. 



Economically, the peat mosses are of more value than any 

 others. In many portions of Ireland and Scotland peat is 

 almost the only fuel supply of the peasantry. In the United 

 States there is an abundant supply of peat. Dana estimates 

 that there are 15,000,000,000 cubic feet in Massachusetts alone. 

 Peat has been taken out of the excavations for the N. Y. City 

 subways. 



SPHAGNUM (Dill.) L. 

 Key 

 (Adapted from N. Am. Flora) 

 1 — Cortical cells of the stem and branches reinforced by spiral fibril-bands 2 

 Cortical cells of the stem and branches without fibril-bands 6 



