xix] FIXATION OF SEEDLINGS 245 



means or an absciss layer. There are exceptions, however, to the 

 general nile that the radicle of water plants is poorlv dev^oped: 

 in Lobelia Dortmanna, for example, it attains feir dimen^ans^. 



In the c=;e of those water plants which grow rooted in the 

 soil, the poor development of the radicle is often cnmpensated, 

 at an early seedling staee, by the production of a garland of verv 

 long root-hairs, which grow out from the * collet,* or junction 

 of hypocotyl and root, e.g. Hrppuris-^ Elutine hexandr^^ (F^- 

 158) and many Helobieae^*, such as ZanmcheJBa (Fig. 159 C, 

 p. 246). This type of seedling is, however, by no mesr- z.-.-.tt 

 to hydrophytes, but is also found in a number of Is.- i : i . : ; . 



The weight of the lir^e seed of _V<f/ar^^, and ci ltlc ache:r:e 

 wall in the case : : :Jie small seedling of ZannichelRi^ (Fis- 1 59>5 

 are sufficient to keep the seedling steady at the boctom of the 

 water until the epicotyl and first leaves are r"d"ced. Other 



_ _ _ _ ^ 



5 eei.::-g-5 are anchored for sorr.etirr.e bv the fruit W2^1 -^r.t is?: ;*> 

 atcvi sirucrures: the =T2.rrliii2ar7irira5of Ctwt. ... ..- .;, 



for instance, has htz-r^ ^Ireadv lef;- t'~ I- T -:.:.. 

 (Fig. i6c, p. 24-) :-r - :-:3n of "r ieei :-r i? 2;: :~r .rjiei 

 in an unusual way, rcr nere the heaw nur ? ir /.- : : : - r : :: ~ 

 of the water, where it is held by hooks derivec :.- : r : - 7 :i--rs:. 

 Two structures of verv unequal size (Cs^ ir.t C -r ^ tr t-ilv 

 interpreted as the two cotyledons, though r rr : "is %-iew 

 is open to re\"i5ion. The hyjxxrotyl, including even ics e: --r~.e 

 ap>ex, which presumably is of root nature, is nesatrveiv re:- 

 tropic. The r?t hteral roots, borne by the hvDOtocyL. cur- e 

 downwards ana anchor the plant in the soiL ^hi.e -rr.iTrr :: :l-e 



1 Buchenau, F. ,'1866,. Innisch, T. (1859^). 



Klebs, G. (1884). * Warming, E. (1883*). 



Hochreutiner, G ^1896'. 'Sec p. 127. 

 " Goebel, K. (1891-1893;. 



