xxiii] ALTITUDE 291 



genus Isoetes, like the flowering plants just mentioned, shows 

 great indifference to altitude. One species, /. amazonica^ ^^^.^ 

 was found on the river margin at Santarem in the lowlands, 

 while another occurred at about the same latitude on the cold 

 Paramos of the Andes at nearly 3700 metres^. In India, Lemna 

 minor has been recorded at Laboul at a height of above 2900 

 metres^. In Venezuela and Tibet, Potamogeton pectinatus^ which 

 flourishes at sea level in England, has been found at heights of 

 above 5000 metres^. 



The term Ecology is used by some botanists in a sense so 

 wide that it becomes almost co-extensive with out-of-door 

 Botany in general. But, if we limit our consideration to that 

 branch of plant study which strictly deserves the name, it does 

 not appear, as far as the present writer is able to judge, that 

 any general ideas of the first importance, bearing upon the 

 study of water plants, have emerged from it, beyond those to 

 which allusion has been made in this chapter. At present 

 Ecology has scarcely passed the stage of a merely descriptive 

 branch of the science; indeed one of its chief promoters* de- 

 scribed it, a decade ago, as "still in its infancy." When it has 

 become more closely linked up with Physiology, we may look 

 to it for further help in solving the complex problems presented 

 by the life of hydrophytes ^. 



In conclusion, it may be suggested that there is room, in the 

 case of aquatic plants, for ecological work of a rather different 

 character from that usually attempted namely, a study of the 

 changes occurring from year to year in the Angiospermic flora 



1 Spruce, R. (1908). 2 Kurz, S. (1867). 



3 Ascherson, P. and Graebner, P. (1907). 



^ Warming, E. (1909). 



5 In addition to the references given in the course of this chapter, see 

 Bruyant, C. ( 1 9 1 4), Massart, J. ( 1 9 1 o), Moss, C. E. ( 1 9 1 3), Nakano, H, 

 (191 1), Pieters, A. J. (1902), Preston, T. A. (1895), Roux, M. le 

 (1907), Schorler, B., Thallwitz, J. and Schiller, K. (1906), Schroter, C. 

 and Kirchner, O. (1902), Thiebaud, M. (1908). On the cultivation of 

 water plants see Monkemeyer, W. (1897). 



19 2 



