xvn] AQUATIC GEOPHYTES 217 



The caddice worms, which also abounded in this dyke, seemed 



to have a great fancy for using the leaflets in constructing 



their cases, and, in consequence, their 



armour was often elegantly crested 



with tiny adventitious plants of Lady's 



Smock. 



In addition to those aquatics which 

 retain their leaves through the winter, 

 there are others which perenniate in 

 or upon the substratum by means of 

 rhizomes or tubers. Plants which adopt 

 this habit, may be described as aquatic 

 geophytes. Limnanthemum (Figs. 22 and 

 23, p. 41), Castalia (Fig. 1 1, p. 26) and 

 Nymphaea (Figs. 10, p. 25 and 1 2, p. 27) 

 are rhizomatous. In some cases e.g. 

 Sagittaria^ certain Potamogetons and 

 Nymphaeaceae special tubers are 

 formed which outlast the winter These 

 afford a means of vegetative multipli- 

 cation, since an individual plant may submerged type growing 



among Utricularia in shallow 



in some cases give rise to numerous poo i, Commissioners' Pits, 

 tubers; a single plant of Sarittaria Upware, June 27, 1914- in 



. .* ., c . each case the terminal leaflet 



Saglttljoha^ for instance, may produce bears an adventitious plant- 

 as many as ten tuber-bearing stolons. let tV he b f e : C ', s ! ngle 



' . much-decayed pinnule bear- 



Another method of vegetative reproduc- ing a well-developed piantiet; 

 tion is illustrated by Littorella lacustris\ ^ ^af si^eTTl AJ 

 which puts out runners in the spring, 



bearing at their apices young plants not easily distinguishable 

 from seedlings; these plantlets become independent by the 

 late summer or autumn. A plant of this species with a runner 

 is shown in Fig. 142, p. 218. 



The most distinctive mode of wintering and of vegetative 

 reproduction found among hydrophytes, is, however, by means 

 of winter-buds or turions ; these specialised shoots, which are 

 1 Buchenau, F. (1859). 



