434 ELONGATION. 



his * Supplement li la flore des Pyrenees,' p. 27, under 

 the name Pota/inogcton hifolium, a plant which Mr. 

 Bentham subsequently discovered to be nothing but a 

 fiowerless variety of Vk.ia Fal)a distorted by its growi,h 

 in water.' 



Elongation of the root This, as already remarked, is 

 more often a variation than a malformation, and is 

 usually due to the presence of water at a distance 

 necessitating growth at the extremities of the root, 

 or to the presence of some obstacle, such as a stone, 

 to avoid which the root elongates till it has passed the 

 obstruction. Occasionally in Crocus corms some of the 

 fibrils may be met with much lengthened and thickened, 

 and invested with a fleshy sheath. It is not certain, 

 however, that these structures are roots ; possibly, nay 

 probably, they may be processes from the stem thrust 

 downwards into the soil, similar to the formations 

 already described in the tulip (p. 85, fig. 39). 



Elongation of the inflorescence. Under this heading it is 

 necessary to consider lengthening of the common rachis 

 in the case of an aggregate inflorescence, and lengthen- 

 ing of the individual flower-stalks, whether they be 

 solitary or portions of a multiple inflorescence. The 

 two phenomena may occur together, but they are quite 

 as often independent one of the other. Thus, among 

 Umbelllferce the umbels are occasionally met with sup- 

 ported on unusually long stalks, while the pedicels of 

 the individual flowers may or not be increased in 

 length ; so also with some of the Composites, or the 

 heads of flowers of some Leguminosce, Trifolium repens, 

 &c. &c. 



Another illustration of the sort is that recorded by 

 M. Fournier, wherein the usually umbellate inflorescence 

 of Pelargonium was, through the lengthening of the 

 main stalk, transformed into a raceme. Among Com- 

 posites a similar change may sometimes be met with. 



' Cat. PlHiit.; Lauf,'.. p. ll.^. 



