128 VI. POLYPODIACEAE. 



§ 4. PTERIDEAE. 



1. Indusia bearing and covering the sori. No. 37. Adiantum. 



1.1. Indusia not bearing, only covering the sori. 



3. Sori submarginal, roundish, distant, terminal on the veins, con- 

 fined to the tops of the sinus^es, 1 to each sinus. Itldusium 

 roundish, small, hardly covering the sorus at full maturity. 



No. 38. Hypolepis. 



S.3. Sori submarginal, either roundish or oblong, close, soon running 



into a submarginal line or linear, uniting the apices of the veins, 



not confined to the tops of the sinusifes. Indusia transversally oblong, 



approximate, contiguous, confluent or linear. 



3. Sori terminal on the veins, free, roundish or oblong, soon 

 confluent into a submarginal line. 



4t. Base of the stipe abruptly tickened, bearing generally + 

 spongy projections on the outer side. Ring oblique, com- 

 plete, as in Cyatheae. Fertile pinnae narrowly linear. 



No. 40. Plagiogyria. 

 <f.4. Base of the stipe not abruptly thickened, without projec- 

 tions. Ring vertical, incomplete. 



5. Vein tips thickened. No. 59. Cheilantes. 



5.5. Vein tips not or hardly thickened. 



e. Fronds divided; leaflets + stalked, not adnate 



to the rachis, . more or less distinctly articulate 



at the base. No. 41. Pellaea, § Platyloma. 



e.S. Fronds simple or divided; segments adnate or 



ioined, not s talk ed, not articulate. 



Stipes with 1 — % free or joining vascular strands. 

 b. Fronds compoundly divided ; lowest pinnulae (secondary 

 pinnae) short, close to the rachis, stipule-like. 



No. 45. Histiopteris. 

 b.b. Fronds simple or divided, if divided/the lowest pinnulae / 

 (secondary pinnae) not stipule-like. 

 c. Fronds divided; leaflets articulate to the rachis. 

 No. 41. Pellaea, § Pleridella. 



