108 CHARACTEE3 Of TRIBES AND GENERA. 



A. Fronds uniform, base dilated. 



* Sorl numerous, irregular. 



f Fronds simple. 

 D. musffifolia (Bl.) (v v.) 



tt Fronds pinnatifid. 

 D. Heraolea (Kze.) (v v.) 



** Sori ohlique serial. 

 t Fronds pinnatifid. 

 D. coronans {Wall.) (v v). 



B. Fronds dimorplwus. 



* Sori ohlique, 1 <o 2 serial. 



t Fronds pinnatifid. 

 D. Fortune! (Kze.') ; D. quercifolia {Linn.} (v v.) 

 ** Sori transversely uniscrial. 

 t Fronds •pinnatifid. 

 D. propinqua {Wall.) (v v.) ; D. Willdenovii {Bory.) 



tt Fronds pinnate {Poronema.) 

 D. diversifolia {R. Br.) (v v.) ; D. glaucistipes {Wall.) 



Obs. — The two last species difTer from the rest in having- 

 pinnate fronds, and are specially marked by having- a 

 small impressed pore at the base of each pinnas, which, 

 with their pinnate fronds, is sufTicient to mark them as a 

 distinct group, under the sectional name of Poronema. 



23. Detostachyum, /. Sm. (1841). 



Surcidum short and thick. Fronds contiguous, sessile, 

 rigid, 1 to 3 feet high, pinnatifid, segments articulated 

 with the rachis, sterile below, the base dilated, the upper 

 segments pinnate, contracted and fertile. Veins of sterile 

 segments costi»form ; venules and veinlets compound 

 anastomosing-, forming nearly equal quadrangular areoles. 



