Sphagnales. 3 
narrow green cells enclosing the large hyaline cells (Fig. 59). The 
latter have their walls thickened by ring-like bars, which are often 
joined up ; these bars are thickest in the cells of the outstanding 
Fig. 56. Sphagnum acutifolium. Portion of a plant, showing two of the 
branch-tufts; in each tuft there are two drooping branches and three out¬ 
standing ones. 
branches, and their thickness varies considerably according to the 
habitat, being greatest in plants growing in exposed or sunny places, 
while the fibres are feebly developed in plants growing in shade or 
in very wet places, and are often absent altogether in more or less 
