CHAPTER XL 



DRYOPTEROID FERNS (I. Woodsieae) 



It has already been suggested that the Cyatheoid type of Ferns, with its 

 constantly superficial sori, has given rise to two phyletic sequences, viz. the 

 Dryopteroids which centre round the genus Dryopteris, and the Blechnoids 

 which centre round the genus Blechmun : and that they differ from one 

 another in the fact that in the former the superficial sori characteristically 

 maintain their individuality, while in the latter they fuse to form longitudinal 

 coenosori (Vol. Il, p. 333). It will be convenient to take the former first, and 

 to see how the individual sorus may undergo modifications that result in 

 that characteristic of the large body of Leptosporangiate Ferns which are 

 associated with Dryopteris. It will be seen how gentle are the steps of the 

 comparison which leads from the Cyatheoid to the Dryopteroid Ferns them- 

 selves, and how on a basis of further comparison these may be held to have 

 advanced to still other derivatives. 



The Ferns in question comprise for the most part, though not wholly, those 

 grouped by Diels under the Woodsieae, and the Aspidieae {Naturl. Pflan- 

 zenfavi. i, 4, p. 159). The Onocleinae were included by Diels under the 

 Woodsieae, but for the moment we may hold them over and apart from 

 the present comparisons. The Woodsieae thus limited (excl. Onocleinae) 

 form a natural link with the Cyatheaceae (excl. Dicksonieae). As accepted 

 by Diels they include Diacalpe Blume (1 sp.), Peranevia Don (i sp.), Woodsia 

 R. Brown (25 sp.), Hypoderris R. Brown (3 sp.), Cystopteris Bernhardi (13 sp.), 

 and AcropJiorus Presl (i sp.). The existence of three monotypic genera 

 among these Ferns itself indicates a probability that they are transitory 

 survivals. This applies especially to Diacalpe and Peranema. The genera thus 

 named will now be examined from a generally morphological point of view 

 but Cystopteris and AcropJiorus will be held over for later discussion (see 

 Chapter XLVIII, on Genera Inccrtae Sedis). 



Woodsia R. Brown 



The genus Woodsia was established by Robert Brown in 18 10. It includes 

 25 species as enumerated in Christensen's Index, and comprises small mountain 

 and rock-dwelling types. The rhizome is upright with nested leaves of rela- 

 tively simple form, and with open venation. The round sorus has a circular 

 basal indusium, laciniate in varying degree at its margin, and the sequence 



