J. SMITH ON THE GENERA OF FERNS. 157 



Ohs. This tribe is represented by the extensive genera 

 Pteris, Adiantwn, and Blachnum, as characterized by Lin- 

 naeus, Swartz, Willdenow, and others. It is readily distin- 

 guished from PolypodieoSf by the sori being furnished with a 

 special indusium which bears the sporangia in its axis of at- 

 tachment, or on its inferior disk, and the same character dis- 

 tinguishes it from AcrostichiecB, with which tribe Pteridiece is 

 connected through Lomaria. 



Sect. I. Chilosore^, J. Sm. 



Sori marginal, round or elongated, continuous, or inter- 

 rupted. 



49. HypoLEPiSj Bernh. Presl. 



Veins forked or pinnate; venules dXxtCi, their apices free, 

 the lower exterior one sporangiferous ; sori terminal, round, 

 marginal ; indusium formed of a reflexed changed venule. 



Fronds /rowi tivo to six feet high, bi-tripiiinate ; laciniae cretm- 

 lated, smooth or pilo-glandidose ; rachis sometimes aculeate^ 

 sori situated opposite the sinus of the lacinice, forming a row on 

 each side of the ultimate midrib. 



Examp. 1. H. tenuifolia, Bernh. 2. H. repens, (Lonchi- 

 tis, Linn. Cheilanthes, Kaidf.) 3. H. aculeata, (Dick- 

 son ia, Spreng.) 



Illust. Plum. Fil. t. 12. Hook. Gen. Fil. t. 67. A. B. 



Obs, This genus is formed of a group of species charac- 

 terized with large decompound fronds, which rise from a 

 lengthened creeping rhizoma, similar in habit to some of the 

 large-fronded species of Polypodiiim, and differing only by 

 the soriferous crenule being altered in texture, and reflexed, 

 forming a simple lateral indusium with the sporangia in its 

 axis, and therefore not distinct in that respect from the fol- 

 lowing genus Cheilanthes; but their whole habit naturally in- 

 dicates them to be a distinct group from the species which 1 

 retain as true Cheilanthes. Hypolepis may also be considered 

 as having some affinity with the tribe Dicksonie^, especially 

 with the group of which DicksonifP pilosiuscida is the type, 



