80 



those which live and blossom through manv succeed- 

 ing seasons to an indefinite period, as trees, and many 

 herbaceous plants. The term biennial is applied to any 

 plant that is produced one year and flowers another, 

 provided it flowers but once, whether that event takes 

 place the second year, as usual, or whether, from un- 

 favourable circumstances, it may happen to he deferred 

 to any future time. This is often the case with the 

 Lavatera arhorea, Tree Mallow, Engl. BoL t. ] 84 1 , 

 and some other plants, especially when growing out of 

 their natural soil or station. Linnaeus justly observes 

 that, however hardy with respect to cold such plants 

 may prove before they blossom, they perish at the first 

 approach of the succeeding winter, nor can any arti- 

 ficial heat preserve them. This is, no doubt, to be 

 attributed to the exhaustion of their vital energy by 

 flowering. Several plants of hot climates, naturally 

 perennial and even shrubby, become annual in our 

 gardens, as the TropcEolum, Garden Nasturtium. 



In the Turnip, and sometimes the Carrot, Parsnep, 

 &c., the Caude.v or body of the root is above-ground 

 and bare, becoming as it were a stem. Linnieus in- 

 deed calls the stems of trees *^ roots above ground ;'* 

 but this seems paradoxical and scarcely correct. Per- 

 haps it would be more accurate to say the caudex is a 

 subterraneous stem ; but we rather presume it has 

 functions distinct from the stem, analogous, as has 

 been hinted /;. 43, to digestion, at least in those plants 

 whose stems are annual though their roots are perennial. 



