238 



BOTANY 



The shoot grows much as in the Bryales, but no midrib is devel- 

 oped in the leaves and no central strand in the stem. The leaves 

 are characterized by the peculiar empty cells between the narrow 

 green cells, and these empty cells usually are marked with thickened 

 bars, and have round holes in them, so that the cells take up water 



C.L 



FIG. 203. Sphagnum acutifolium. Development of the embryo. (After WALDNER.) 

 (A, B, E, F, X 350; C, X 315; D, X 150.) 



very quickly. Similar empty cells form the cortex of the stem, 

 and also soak up great quantities of water, so that the masses of 

 growing plants take up water like a sponge. The empty cells give 

 them a pale green color. 



The sporophyte develops no seta, but the end of the shoot to which 

 it is attached often grows out beyond the leaves, forming a " pseudo- 



