MORPHOLOGY OF THE ROOT. 33 



the two under the common appellation of MONOCARPIC plants, 

 Planttz monocarpicce, taken in the sense of only once-fruiting 

 plants ; and to designate perennials by the corresponding term 

 of POLYCARPIC, Plants polycurpica, literally many-fruited, taken 

 in the sense of many-times fruiting. 1 



57. But the distinction even here is no more absolute than 

 that between annuals and biennials. For example, it is not 

 quite clear whether the Cardinal Flower and related species of 

 Lobelia should be ranked as annuals, biennials, or perennials. 

 The plants may blossom and seed toward the end of the season 

 in which they came from seed ; or, germinated in autumn, the 

 small seedlings may survive the winter ; but whenever fructified 

 the fibrous-rooted mother plant dies throughout ; yet usually not 

 before it has established, and perhaps detached from the base, 

 small offsets to blossom the next season ; and so on. Then 

 Houseleeks (Sempervivum) and such-like fibrous-rooted succu- 

 lent plants multiply freely by offsets which are truly perennial 

 in the sense that they live and grow for a few or several years ; 

 but when at length a flowering stem is sent up producing blos- 

 som and seed, that plant dies as completely and in the same 

 manner as any biennial, only the generation of offsets surviving. 

 The same is true of the Century plant (Agave Americana, 

 wrongly denominated American Aloe), which vegetates in the 

 manner of the accumulating stage of a biennial, except that 

 this continues for several or very many years, while the flower- 

 ing stage, when it arrives, is precipitated and terminated in a 

 single season. 



58. Although the stem usually sends forth roots only when 

 covered by or resting on the soil, which affords congenial dark- 

 ness and moisture, yet these are in some cases produced in the 

 open air. Roots may likewise subserve other and more special 

 uses than the absorption of crude or the storing of elaborated 

 nourishment. 



59. Aerial Roots is a general name for those which are pro- 

 duced in the open air. One class of these may serve the office 

 of ordinary roots, by descending to the ground and becoming 

 established in the soil. This occurs, on a small scale, in the 

 stems of Indian Corn ; the lower nodes emitting roots which 

 grow to the length of several inches before they reach the ground 



1 These terms or some equivalents have a convenience in descriptive 

 botany. But those employed by DeCandolle are not happily chosen, as lias 

 often been said. MontStocous (bearing progeny once) and Polytocous (bearing 

 many times) would be more appropriate. 



