324 



ECOLOG V. 



full exposure to the sun and wind, have served to lessen its 

 influence and importance. But where protected from the 



wind, to a large extent from the 

 heat of the sun, and supplied with 

 a suitable moisture condition, the 

 sphagnum flourishes. It grows 

 either alone in shallow water, en- 

 croaching more and more on the 

 centre of the basin, or follows after 

 and anchors among water-loving 

 grasses and carices. In some cases 

 it may thus largely cover such earlier 

 formations. An examination of the 

 sphagnum plant shows us how well it 

 is adapted to flourish under such con- 

 ditions. The main axis of the plant 

 bears lateral branches nearly at right 

 angles, but with a graceful downward 

 sweep at the extremity. These pri- 

 mary lateral branches bear secondary 

 branches, which arise, usually several, 

 from near the point of attachment 

 to the main axis. They hang down- 

 ward, overlap on those below, and* 

 completely cover the main axis or 

 stem. The leaves of sphagnum are 

 peculiarly adapted for the purpose of 

 taking up quantities of water. Not 

 all the cells of the leaf are green, 

 but alternate rows of cells become 

 broadened, lose their chlorophyll, 

 and their protoplasm collapses on the 

 inner faces of the cell walls in such 

 a way as to form thickened lines, giving a peculiar sculpturing 

 effect to them. Perforations also take place in the walls. These 



Fig. 267. 

 Two fruiting plants of sphagnum. 

 (From Kerner and Oliver.) ■ 



