30 HISTORY OF BRITISH FERNS. 



The proportion borne by the Ferns to the whole mass of 

 flowering plants, in the torrid zone, is stated at one in 

 twenty ; in the temperate zone at one in seventy ; and in 

 the frigid zone at an average of one in eight. In the most 

 northern parts of the Arctic zone, none have yet been dis- 

 covered. 



In onr own country, the proportion borne between these 

 two great divisions of vegetation, is reckoned at one Pern 

 to thirty-five flowering plants. In Scotland they stand re- 

 latively as one in thirty-one. 



The forms which exist among the Ferns are very diversi- 

 fied, and this, no less than their variations of size and habit, 

 renders them conspicuous objects in the scenery where they 

 abound. They may all be classed under three divisions, so 

 far as their leading features are concerned, namely, arbores- 

 cent, shrubby, and herbaceous. 



It is the former class, the arborescent species, chiefly, 

 which exert a marked influence on the physiognomy of 

 nature, for, as Meyen well remarks, they unite in themselves 

 the majestic growth of the Palms, with the delicacy of the 

 lower Ferns, and thus attain a beauty to which nature shows 

 nothing similar. These truly arborescent species are prin- 

 cipally confined to the torrid zone, their slender waving 



