CHAPTER XLII 



ASPLENIOID FERNS 



The Aspienieae, as grouped by Diels {Nat. Pflanzenfani. I, 4, p. 222), com- 

 prise an apparently compact body of fifteen genera. The diagnosis which 

 he gives is drawn in somewhat general terms, and does not take into account 

 the genesis of the structures there designated as "sori." Though these have 

 a superficial similarity throughout the group thus assembled, there is now 

 sufficient evidence to show that they have originated from two distinct 

 sources. The one is by extension and modification of form of the individual 

 sorus of the type oi Dryopteris: the other is by fusion of sori into elongated 

 coenosori, as in Blechnum, which may subsequently be disintegrated, though 

 not necessarily along lines corresponding to the original fusion. There are 

 thus two lines phyletically distinct, which are confused under the heading 

 Aspienieae as applied by Diels. 



The group is, however, divided by him into (i) Aspleniinae, and (2) 

 Blechninae, which respectively correspond roughly with the distinction in 

 phyletic origin. The Aspleniinae include for the most part those genera in 

 which the sorus has been a unit throughout descent, though subject to 

 modification in form: the Blechninae include genera in which the "sorus" is 

 not a unit, but the whole or part of a coenosorus, soral fusion having played 

 its part in their evolution. But the distinction as drawn by Diels is not a 

 clean cut between the two. Certain genera, and in particular Scolopcndrium 

 ( = Phyllitis Ludwig), will have to be transferred from the Aspleniinae of 

 Diels to his Blechninae if the distinction is to be a phyletic one. The grounds 

 for this will be stated in detail later. It will be desirable to accentuate this 

 distinction by segregating the treatment of these phyletically distinct lines. 

 The present Chapter will deal with those Ferns which may be designated 

 "Asplenioid," in the sense that they share with the genus Asplcniuvi the 

 fact that the sorus is a definite unit: while a later Chapter will treat of the 

 Blechnoid Ferns in which fusion has led to the formation of a coenosorus. 



The Asplenioid Ferns thus defined include the genera At/iyriuin Roth 

 (1799, 86 species), Diplaziiim Swartz (iSoi, 208 species), Diplaziopsis C. Chr. 

 (1906, I species), Asplenium Linn. (1753, 429 species), CeteracJi Adanson 

 (1763, 4 species), and Pleurosorus Fee (1850, 3 species). 



Fig. 669. Vxg. 7,\, a, b= Phyllitis Scolopendrium (L.) Newm. a = very young sorus cut vertically. 1/ = 

 the same older, with veins, protecting " indusial " flaps, and the first sporangia ( x 125). Figs. 32-35 = 

 Asplenium, showing venation and sori ( x 3). Fig. y.. — Asplenium obtiisatnm Forst. Fig. ^J, = Asple- 

 11 ill III horridiim Kaulf. Fig. 1^, = Asplenium serra Langsd. and Fisch. Fig. 35 = Asplenium (Diplazium) 

 celtidifohum Kze. Fig. 36, a-c = Asplenium obtiisatnm Forst., sections of fertile pinnae, showing 

 successive stages of development of the sori. (« and b x 125: c x 50.) 



