.315 



insoluble in water and in alcohol. It contains also the subcarbonate, sul- 

 phate, and hydrochlorate bf potash, carbonate and pluosphate of lime, alu- 

 niine, silex, and oxyde of iron. Brewster, 2. 176. The roots of Nephrodiuni 

 esculentum are eaten in Nipal, accordini; to Dr. Buchanan. Don Prodr. 6. 

 Those of Ang:i9pteris evecta are used for food in the Sandwich Islands, under 

 the name of Nehai. Diplazium esculentum, Cyathea medullaris, Pteris 

 esculenta, and Gleichenia dichotoma, are also occasionally employed for food 

 in different countries. Pteris aquilina and Aspidium Filix Mas have even 

 been used in the manufacture of beer, and Aspidium fragrans as a substitute 

 for tea. Agdh. 



Examples. Ferns have been divided into several sections, of which the 

 following are the most generally adopted : — 



I. POLYPODIACE.!,. 



Gyratse, Swartz Synopsis Filicum, (1806). — Filices verse, Willd. Sp. PI. 

 5. 99. (1810). — Polypodiaceee, R. Brown Prodr. 14'5. (1810); 

 Agardh Ajjh. I] 6. {IS22); Kaulfuss EHU7neratio, 55. {1824); Bory 

 in Diet. Class. 6. 586. (1824.) 



Thecae furnished with a vertical, usually incomplete, annulus ; burstino- 

 irregularly and transversely. (Polypodium, Pteris, Adiantum.) 



II. Gleichene;e. 



Schisraatppterides, Willd. I. c. 69. (1810). — Gleichenese, E. Br. I. c. 160. 



(1810); Kaulfuss I. c. 36. (1824); Bory, I. c. (1824.) 



Thecse furnished with a transverse, occasionally oblique, annulus, nearly 

 sessile, and bursting lengthwise internally. (Platyzoma, Gleichenia, Mer- 

 tensia.) 



III. OSMUKDACE^. 



Osraundaceee, R. Br. I. c. 161. (1810); Agardh I. c. 115. (1822) ; Kaulfuss 

 I. c. 42. (1824) ; Bory I. c. (1824.) 



•ThecGe without any annulus, reticulated, striated with rays at the apex, 

 bursting lengthwise, and usually externally. (Osmunda, Schizaea, Lygo- 

 dium.) 



IV. DAN.^lACEiE. 



Agyratse, Swartz Synops. (1806). — Poropterides, Willd. I. c. 66. (1810). — 

 Daneeacege, Agardh I. c. 117. (1822). — Marattiacese, Kaulf. I. c. 

 31.(1824); Bory ;. c. (1824.) 

 Thecae sessile, without any ring, concrete into multilocular sub-immersed 



masses, opening at the apex. (Marattia, Danaea.) 



V. Ophioglosse.e. 

 Ophioglosseee, R. Br. I. c. 163. (1810) ; Agardh Aph. 113. (1822) ; Kaulfuss 

 L c. 24. (1824) ; Bory I. c. (1824.) 

 Thecae single, roundish coriaceous, opaque, without ring or cellular reti- 

 culation, half 2-valved. Vernation straight. (Ophioglossura, Botrychium.) 

 To which Dr. Hooker adds : — 



Parkeriace.e. 



Parkeriaceae, Hooker Exot. Fl. t. 147.(1825); t. 231. (1827) ; Hooker et 



Greville Icones Filicum, t. 97. (1828.) 



Thecae scattered, sessile, marked with a broad, almost obsolete, very 



short annulus, which is sometimes distinct and nearly complete. Sporules 



large, 3-cornered, striated. (Parkeria, Ceratopteris.) 



