204 



HUTCHINSON'S POPULAR BOTANY 



siderable distance, and " is surmounted by a perfectly vertical crest, 

 gradually diminishing in size as the root recedes from the trunk, but 

 often three or even four feet high near the base. These crests, which 

 are very thin but perfectly smooth, regularly follow all the sinuosities 

 of the root, and thus form, for a considerable distance round the tree, 

 a labyrinth of the strangest appearance. Large spaces of swampy 

 ground are often covered with their windings, and it is no easy matter 

 to walk on the sharp edges of their vertical bands, whose interstices 

 are generally filled with deep mud. On being struck, the larger crests 

 emit a deep sonorous sound, like that of a kettle-clrum." They are not 

 true aerial roots, nor even epigeous roots, but rather roots of a sub- 

 terraneous origin, which have been pushed through the yielding oozy 

 soil in order to obtain the oxygen which is absent in the water-logged 

 soil. The Marsh Cypress in a similar manner sends up woody growths 

 from its buried roots^in! order to conduct oxygen to them. 



Photo by] 



FIG. 256. DANDELION (Taraxacum officinale). 



[E. Step. 



All the florets in this familiar Composite flower have strap-shaped corollas, thus differing from Composites like 



the Daisy, which has only the outer row strap-shaped. Owing to its buoyant seeds, the Dandelion is widely 



distributed, being found in all cold and temperate regions. 



