2i 4 VEGETATIVE REPRODUCTION [CH. 



the banks of the creek. If you are in a canoe, it gives you little 

 apprehension to know you have got to go through it, but 

 if you are in a small steam launch, every atom of pleasure in its 

 beauty goes, the moment you lay eye on the thing. You dash 

 into it as fast as you can go, with a sort of geyser of lettuces 

 flying up from the screw; but not for long, for this interesting 

 vegetable grows after the manner of couch-grass. I used to 

 watch its method of getting on in life. Take a typical instance : a 

 bed of river-lettuces growing in a creek become bold, and grow 

 out into the current, which tears the outside pioneer lettuce 

 off from the mat. Down river that young thing goes, looking 

 as innocent as a turtle-dove. If you pick it up as it comes by 

 your canoe and look underneath, you see it has just got a stump. 

 Roots? Oh dear no! What does a sweet green rose like that 

 want roots for? It only wants to float about on the river and be 

 happy; so you put the precious humbug back, and it drifts 

 away with a smile and gets up some suitable quiet inlet and 

 then sends out roots 1 galore longitudinally, and at every joint 

 on them buds up another lettuce; and if you go up its creek 

 eighteen months or so after, with a little launch, it goes and 

 winds those roots round your propeller 2 ." 



The luxuriance of hydrophytes as compared with other herba- 

 ceous plants can be demonstrated not only by examples of their 

 multiplication on a large scale, but also when the dimensions 

 of individuals are considered. A striking instance is afforded 

 by Caspary's 3 measurements of the leaves of a plant of Victoria 

 regia cultivated in a hot-house; the maximum growth of the 

 lamina recorded in 24 hours was as much as 30-8 cms. in length 

 and 36-7 cms. in breadth. Even in our climate the growth of 

 aquatics must be rapid, to produce the length of stem some- 

 times observed; in the case of Ranunculus fluitans, shoots twenty 

 or more feet in length have been recorded 4 , while floating 



1 Botanically these " roots " are of course lateral stems. 



2 For other cases of plant accumulations which are on a sufficient 

 scale to form serious obstructions, see Hope, C. W. (1902). 



3 Caspary, R. (18562). 4 Schenck, H. (1885). 



