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CHAPTER III 



THE LIFE-HISTORY OF THE NYMPHAEACEAE 

 AND OF LIMNANTHEMUM 



THE Nymphaeaceae, like the Alismaceae dealt with in 

 the last chapter, are a typically aquatic family, but, in 

 the Nymphaeaceae, the water habit has become even more 

 firmly established than in the Alismaceae, land forms being 

 relatively rare. The dominant type of leaf has a floating blade, 

 whereas, although this form of leaf occurs among the Alisma- 

 ceae, it occupies as a rule a minor place. The rhizome again, 

 which is seldom a conspicuous organ in the Alismaceae, as- 

 sumes considerable importance in the case of some Nymph- 

 aeaceae, although the family includes also a number of annuals. 

 Our British Waterlilies perenniate by means of rhizomes; 

 these are rich in starch and in the case of some foreign species 

 are used for food^. That of the Yellow Waterlily is epigeal^, 

 with the result that small specimens are occasionally torn from 

 their moorings and found among river drift. The hypogeal 

 rhizomes of the White Waterlily, on the other hand, can seldom 

 be obtained unless they are actually dragged up with a boat- 

 hook out of the mud. The rhizome of Nymphaea lute.a^ L.^ is a 

 very striking object (Fig. lo A). It is slightly flattened and of 

 a greenish colour on the upper surface, but pallid and yellowish 

 below. It is decorated with the scars of the leaves (/.j.) of 

 previous years punctuated by the vascular strands which 

 supplied them and also with the scars of the peduncles (/).^.), 

 which can be distinguished by their rounded form. With each 

 leaf-base, three roots are usually associated; at r^ these roots can 



1 Paillieux, A. and Bois, D. (1888). 



2Royer, 0.(1881-1883). 



3 ^ Nuphar luteum, Sibth. et Sm. 



