72 



LETTERS ON TREES. 



the changes which these and their roots respectively 

 undergo, — and in the habitudes of their respective off- 

 spring. Thus the stem of the tree-plant grows above 

 ground, that of the potato-plant under ground ; the 

 dead stem and roots of the tree-plant continue unde- 

 composed and entire for years and ages, those of the 

 potato-plant decay early the following year — its roots 

 perishing, in fact, the same year with the leaves ; 

 the offspring of the tree-plant grow together, and 

 as parasites on the persistent dead remains of their 

 parent, which serve as a common axis on and around 

 which they grow — those of the potato-plant strike 

 down singly and separately into the soil, and have 

 no connection with any portion of their parent, the 

 remains of which have in fact ere this stage of their 

 growth wholly disappeared, — and nothing left around 

 which, as a common centre and a mechanical support, 

 they could grow as parasites. Had it suited the pur- 

 poses, immediate and remote, which the Author of 

 ^fature had in view in giving them existence, we might 

 have had the respective peculiarities of these two kinds 

 of plants completely reversed. The potato-plant and 

 its progeny might have grown together parasitically, 

 and by their aggregation have formed a true potato- 

 tree. Fantastic, doubtless, would have been the aspect 

 of such a tree ; but it would have possessed, as a whole, 

 the same individuality which common opinion ascribes 

 to an ordinary tree, and the several plants composing 



