THE SPHAGNUMS (SPHAGNALES) 



423 



the lack of drainage, organic acids accumulate and prevent the 

 action of Molds and Bacteria, the dead remains of Sphagnum and 

 accompanying plants do not decay, but are finally transformed 

 into peat, which is a valuable 

 fuel in some countries, espe- 

 cially in Ireland. 



Both antheridia and arch- 

 egonia are stalked and are 

 produced on branches. The 

 sex organs differ from those of 

 the Bryales in their develop- 

 ment but are quite similar in 

 appearance when mature. 



The sporophyte differs from 

 the sporophyte of the Bryales 

 in having only a very short 

 seta, which is only a neck be- 

 tween the foot and the capsule. 

 In connection with this fea- 

 ture there occurs another 

 characteristic feature known 

 as the pseudop odium. The 

 pseudopodium, which replaces 

 the seta in function, is formed 

 by the elongation of the axis 

 of the gametophore just be- 

 neath the sporophyte, which 

 is thereby carried up as if it 

 were on an elongating seta. 

 Another peculiar feature of 

 the sporophyte is that the 



columella does not extend entirely to the top of the spor- 

 angium as in Bryales, but the sporogenous tissue arches over 

 the columella. In this respect the sporophyte is like that of 

 Anthoceros. 



When the spores germinate, instead of producing a filamentous 

 protonema, they produce a flat thallus that resembles a Liver- 

 wort, and from buds on this thallus the leafy gametophores arise. 

 When studied in detail one finds that Sphagnum has a number 

 of features characteristic of Liverworts and a number that are 



FIG. 377. The gametophyte and 

 sphorophyte of Sphagnium. At the 

 left, gametophyte of Sphagnium; at 

 the right, a sporophyte and the pseudo- 

 podium; between, a vertical section 

 through the sporophyte, showing the 

 short rounded foot, the short neck-like 

 seta, and the globular sporangium in 

 which the spores are borne in a cavity 

 forming an arch over the columella. 



