Fructification. 31 



or less covered by the inroUed edge of the frond. The venation is 

 very obscure. 



39. Adiantum. — The maidenhairs have a peculiarly smooth 

 foliage and usually possess no midvein. The veins are usually 

 flabellate, and after forking once or more times bear the sori at 

 their extremities. The margin of the frond is reflexed thus form- 

 ing an indusium which bears the 

 sporangia on its under surface. 



40. Pteris. — (Fig. 7). In this 

 genus, which includes the common 

 brake, the otherwise free veins are | 

 united by a filiform receptacle 

 which bears the sporangia. This 

 continuous marginal line of fructi- '*'''' ^^^'''''^ ^^ ^M/mv /'j/ ^//// a 

 fication is covered by a membra- ^'s- ^■ Pterin lovgijolia, l. Enlarged 



, . _ 1 r 1 segnient of pinna showing the vein-like 



nous mdusmm formed of the mar- .^..pj^i^^^^,,. ^^^ marginal indusinm. 

 gin of the frond. (Original.) 



41. Cheilanthes. — The lip-ferns found within our limits are 

 unequally divided among four sections, all agreeing in bearing 

 the sori at or near the ends of the veins covered by an indusium 

 formed of the margin of the frond. 



In Adiantop'sis the indusia are distinct and confined to a 

 single veinlet. Our species varies from the typical species of this 

 section and has even been assigned to a separate genus. 



In EucHEiLANTHES the indusia are more or less confluent but 

 not continuous, usually extending over the apices of several vein- 

 lets. 



In Physapteris the ultimate segments are bead- like, and the 

 indusium is continuous all round the margin. 



Aleuritopteris has the fronds farinose below, and includes 

 a single species somewhat doubtfully assigned to our limits. 



42. Cryptogramme has dimorphous fronds, the margins of the 

 fertile being closely rolled toward the midvein thus covering the 

 confluent sori. At maturity these open flat in order to discharge 

 the spores. 



43. Pellsea has representatives of three sections within our 

 limits all agreeing in possessing intramarginal sori which finally 

 become confluent and form a marginal line covered by an indu- 

 sium formed of the margin of the frond. 



Cheiloplecton includes herbaceous species with visible veins 

 and broad indusia. 



