THE RINGED FERNS. 



113 



The stems of Marattia and Angiopteris are of a mucila- 

 ginous mealy nature, and are eaten by the natives of some 

 of the Pacific Islands. 



Ferns rank as one of the widest spread families in the 

 vegetable kingdom, being found in greater or less numbers 

 in all cHmates between the most northern and southern limits 

 of vegetation, and at elevations ranging from the sea level to 

 14,000 or 15,000 feet within the tropics. Comparatively 

 few species are found in open, thinly wooded places, such 

 districts being often occupied by one of the most gregarious 

 and abundant of all ferns — the common brake (Pteris aqui- 

 lifia), which occupies large tracts of the earth's surface. 

 With regard to the number of species in this family, great 

 diversity of opinion exists, much of what has already been 

 written about them having been derived from portions of 

 fronds only, which are so variable that even parts of the same 

 fi'ond have been described as distinct species. In the Species 

 Filicum of Sir William Hooker, nearly 2300 are described ; 

 but as new forms are continually being discovered, 2500 may 

 with propriety be given as the approximate number. 



THE EINGED FEKN FAMILY. 



(POLTPODIACE^.) 



Fronds bearing spore cases {sporangia) on their imder sur- 

 face or margin, or on contracted {rachiforiii) fronds. Spore 

 cases, membranous, generally pedicellate, and furnished with 

 a vertical or horizontal jointed ring {anniiliis) . 



This family comprehends the greater number of known 

 ferns, and presents two very distinct modes of growth. The 

 first, Eremohrya, having the fronds jointed (articulated) with 

 the axis of growth {rhizome) ; the second, Desmohrya^ in 

 which the fronds are adherent and continuous with the axis, 

 forming a sarmentum or erect caudex. 



The following are the sectional divisions of this family: — 



I 



