252 TASMANIAN BRYOPHYTA, 



U.S. TAS. 



a short broad sheathing base and subulate lamina, patent, 

 at the apex curved to form a sickle shaped point. 2 mm. 

 papillose on the external surface; nerve broad, occupying 

 nearly the whole lamina. Perichaetials longer, erect. Cap- 

 sule shortly exserted. 



Common on sub-alpine rocks in wet places. 



Fam. 18— SPHAGNACEAE. 



Large gregarious mosses forming dense masses in moist 

 situations or submerged in ponds. Perennial, the central 

 stem elongating at the apex, the branches usually in fas- 

 cicles and always of limited growth, some of the branches 

 of each fascicle are relativel}'- robust, divergent to sub- 

 erect, while others are slender and pendulous, lying close to 

 the stem. Leaves nerveless, thin, of a single cell layer, 

 composed of two forms of cells, namely, large thin-walled 

 tracheids strengthened with annular or spiral fibres and 

 usuallv pierced with few large pores, contained in a reticu- 

 lation of linear, chlorophyllous cells. Rarely the develop- 

 ment of the tracheids is arrested and all the cells remain 

 similar and chlorophyllous. Antheridia globose, stalked, 

 solitary in the axil of a bract and clustered in lateral 

 rather dense strobili. Archeojonia solitary or few at the 

 apex of a branch, concealed by relatively long leaves. Cap- 

 sule globose, with a minute lid. without annulus or peri- 

 stome ; not developing a seta but bearing only a short foot 

 inserted on the apex of a peduncle which is a leafless pro- 

 longation of the parent branch. Protonema a flat expan- 

 sion of a single cell thickness. 



The family contains but one genus, Sffhagnum, specialis- 

 ed to suit peculiar conditions and not continuous with any 

 other group. In many text-books the spores are stated 

 to be of two forms, large and small, and efforts have been 

 made to prove sexual distinctness of these, but Campbell 

 states that Nawaschin has conclusively shown that the so- 

 called microspores are the spores of a parasitic fungus. The 

 peduncular elongation of the axis is similar to the condi- 

 tion found in Andreaea, and the structure of the leaves 

 roughly recalls the tissue of Leurohryum, but in each it is a 

 case of similar adaptation and does not imply relationship. 



Sphagnum (Dill.) Ehrh. 

 The character is sufficiently indicated in the description 

 of the Family. The species are variable and difficult to 

 diagnose, and are constantly being re-arranged by special- 

 ists working at the group. The following is near the latest 



