LECT. IV.] THE ROOT. 143 



names by which they are known to Botanists ; and 

 under one or other of these species, with very few 

 exceptions, every variety of root may be classed. 

 One exception only is necessary to be particularly 

 noticed as it refers to a root, which is frequently 

 improperly quoted by elementary authors as an 

 example of a root bearing pendulous tubers like 

 the Potatoe; although, in fact, it is merely a 

 conical root with thick lateral rootlets swelled, near 

 the extremity of each, into a solid nodule. This 

 form of root is the Radix JUipendula of authors ; 

 as exemplified in the root of Common Dropwort, 

 Spirea Jilipendula (fig. o), which is in strict 



o. 



language a nodose root, the tubers or knobs being 

 perennial, actually parts of the root, and reservoirs 

 of nutriment for the use of the plant itself, pro- 



