92 BRITISH CHAROPHYTA. 



of stout water-cord about J inch thick, and twenty 

 yards will generally be found sufficient. The drag can 

 be thrown from the shore, or, better still, where the 

 water is deep, be used from a boat. 



Thus equipped the collector will find himself within 

 reach of most water beds that he may desire to explore. 



The Charophytes with their delicate structure can 

 seldom hold their own with stronger vegetation. Old 

 ditches and pools therefore which show any large growth 

 of other water-plants seldom yield Charophytes. Then- 

 favourite habitat is a newly-dug or newly-cleaned ditch, 

 or a clay pit where stronger vegetation has not yet 

 estabhshed itself. They are frequently found in abun- 

 dance in lakes and rivers, but usually in massed growth 

 for support and protection. 



It has to be borne in mind that many Charophytes 

 are both local and fugitive. A species may be found 

 in lake or other piece of water in some one quite re- 

 stricted area, while the rest of the water shows no sign 

 of the plant. Again, a species which grows in abundauce 

 one year may be wholly absent from the same spot 

 another year. Thus the collector needs to search a 

 water area in all its reaches and for several years before 

 he can be satisfied as to the various species which that 

 area yields. 



Plants should, if possible, be collected at the various 

 stages of the(ir development, but it is specially important 

 to secure specimens in their full fruiting state. This is 

 particularly important in the case of the Nitelleae. N. 

 flexilis cannot be distinguished with certainty from 

 N. opaca when the fruit is absent, and in the case of 

 dioecious species the sexes can only be distinguished by 

 their gametangia. Except when quite out of season 

 fruiting specimens can generally be found with a little 

 searching. 



When a specimen has been brought to the surface it 

 will usually require a considerable amount of washing 

 to free it from, the mud and from other matter collected 

 in its branchlets. This can best be done by holding 



