208 CONSERVATIVE ORGANS. [LECT. V. 



observed the same mortality to occur, in any 

 degree, in the roots of trees when growing, under 

 favourable circumstances, in their natural situa- 

 tion *." My own experience does not authorize 

 me to decide with confidence on this question; 

 but it rather induces me to incline to the opinion 

 that they are annual productions. 



In duration, roots are either annual, biennial, 

 or perennial. Annual roots belong to those plants 

 which are produced from the seed, grow to their full 

 extent, and die in one year or season ; as, for ex- 

 ample, Barley, Hordeum secale; the White Poppy, 

 Papaver somniferum ; the common Pea, Pis urn 

 sativum ; the garden Bean, Vicmfaba, &c. : bien- 

 nial to those that live through the winter of the 

 year in which they are produced, and after flower- 

 ing and yielding seed, die in the following year, 

 as the Carrot, Daucus car of a ; the genus Teasel, 

 Dipsacus ; the Canterbury Bell Flower, Campa- 

 nula medium, &c. : and perennial to those that 

 blossom and produce seeds through many suc- 

 cessive seasons, as the majority of herbaceous 

 plants and all shrubs and trees. But the life of 

 annual and biennial roots may occasionally be 

 protracted much beyond its natural period, when 

 any circumstance occurs that can prevent the 

 plant from flowering, or, even when it does flower, 



* Phil. Trans. Part 1. 1809. 



