Reconquest of the Water 



But to be quite frank about this subject, the reader 

 ought first to spend six months in careful microscopic 

 examination of all the algae and diatoms to be found 

 in all the ponds and rivers in his district, then he should 

 try to describe them, preferably in dithyrambs or 

 leonine verses and not in plain prose. 



On the shores of many of our fresh-water lakes and 

 tarns one finds occasionally another very curious and 

 unusual flora. The plants are submerged and consist 

 of tiny leaf rosettes which are exceedingly like one 

 another except when in flower, although as different 

 botanically as they well could be. There are species 

 of Litorella (Plantaginaceae), Lobelia Dortmanni, Subu- 

 laria (Cruciferae), Isoetes, Heleocharis acicularis, &c.'^ 



These little rosettes of linear leaves are generally 

 planted amongst stones, which as well as themselves are 

 covered over with the usual golden-brown diatom crust, 

 or with entangled webs of algae. 



It is said that it is specially where the waves are 

 strong; and perhaps where the ice grinds along the 

 shore in winter, that this Litorella association replaces 

 reeds and marsh plants. 



Along many of our Scotch rivers also, a very inter- 

 esting process can be followed. The river flows 

 between banks some 7 to 10 feet high, which it 

 has cut out of its flood plain. At the foot of these 

 banks, certain plants are always trying to establish 

 themselves, and especially where the water is shallow. 

 The most prominent is Phalaris arundinacea, a grass 

 whose tough rhizomes are tied down amongst the 

 stones by strong anchoring roots. This grass is very 

 important to the, neighbouring proprietors, whose land is 

 being saved by it from the constant encroachments of 

 the current when in flood. 



* Vallisneria, which is not British, is extremely similar. 



138 



