198 HUTCHINSON'S POPULAR BOTANY 



of humus, they perish soon after germination ; whereas when sown on the 

 bark of a tree, they not only germinate, bnt grow up with ease into hardy 

 plants." 



Many interesting cases are recorded of plants which, though in their 

 normal state exhibiting no peculiarity of root growth like Banyan, Orchis, 

 or Pandanus, yet have put forth adventitious roots from the most unlikely 

 places when circumstances of an extraordinary nature made special demands 

 upon their powers. It is affirmed of the Field Maple (Acer campestre) 



Photo by] \_E. Step. 



FIG. 250. FIELD MAPLE (Acer campestre). 



The green flowers and leaves are shown of the natural size. The former are succeeded by winged fruits, similar to 

 those of Sycamore, but with the two wings horizontal. EUROPE, N. and W. ASIA. 



that if you plant it upside-down the buried stem will put forth roots, 

 and that the tree sustains no injury by such treatment. Not every plant 

 is able to accommodate itself thus nicely to circumstances ; yet there 

 can be no doubt that a similar latent vegetative power exists in a great 

 number of plants. Take the Silver Birch (Betula alba) for an example. 

 Some sixty years ago one of these trees was blown down in the Birch wood 

 of Culloden, "and fell," says a writer in Science Gossip, "right across a 

 deep valley or ravine, which it completely spanned ; and the top branches 

 took root on the other side. From the parent stem no less than fifteen 



