A GENERAL SURVEY 15 



and horsetails) with a membership of less than 

 4,000. Naturally these figures vary from 

 year to year as fresh species are discovered, 

 and the matter is still further complicated by 

 the fact that there is a tendency in some 

 directions to call many varieties distinct types. 

 Still, on the whole, we may take the figures as 

 approximately correct, in so far as they give 

 an idea of the numerical strength of the various 

 groups. 



Although the flowerless plants cannot often 

 be called a predominant feature in any part of 

 the world, yet they show a remarkably wide 

 distribution. They contrive to get far nearer 

 to the Poles than any of the more highly 

 speciahsed plants. Quite a formidable list of 

 lichens and algae could be prepared showing 

 those kinds which live right in the Arctic circle, 

 where there is practically snow all the year 

 round. The so-called " red snow," for instance, 

 is due to the presence of certain little algae 

 which give a singular crimson tinge to the 

 white expanse. Many large and vigorous sea- 

 weeds grow in the Arctic Ocean, where the 

 temperature is never more than a point or so 

 above freezing. 



