INTRODUCTION. 9 



Mr. George West in 'A Comparative Study of the 

 Dominant Phanerogamic and Higher Cryptogamic 

 Flora of Aquatic Habit in Three Lake Areas of 

 Scotland ' (1905) records the occurrence in Loch 

 Uanagan, of G. frag His or G. delicatula in 6 to 20 

 feet of water and iV". opaca in 10 to 30 feet, while, 

 carpeting lakes at Lismore, he found G. desniacantha 

 from 2 to 20 feet, G. delicatula from 10 to 20 feet, 

 and G. rudis from 25 to 35 feet. In the Swiss lakes 

 Charophytes have been found at much greater depths. 



The Charophytes are essentially gregarious in 

 character, commonly occurring in dense masses with 

 little or no intermixture of other plants. Often on 

 the shallow margins of ponds and lakes small isolated 

 tufts are to be found, but these are almost always 

 merely outliers of larger colonies. 



Though often growing in water with a sandy or 

 peaty bottom, it is on thick soft mud that Charophytes 

 perhaps flourish most freely, and, for this reason, the 

 ditches of our Eastern Fen Country, and the Norfolk 

 Broads, are particularly prolific in these plants. In 

 Hickling Broad alone no less than twelve species have 

 been found, while from the Lac de Grand-Lieu, a 

 large piece of water in Dept. Loire Inferieure, near 

 Nantes, Monsieur Gadeceau records the astonishing 

 number of seventeen. Newly-made pits, such as those 

 excavated for gravel and clay, are, at an early stage 

 of their existence, also very favourable habitats, being 

 often carpeted with one or other of the common species, 

 to the exclusion of any other plants. In such situations 

 however, after a few seasons, the Charophyte gives 

 place to, or is ousted by, other vegetation, and by the 

 time the large coriaceous floating-leaved plants, sucli 

 as Potamogeton natans and the water-lilies, have 



