GYMNOGRAMMOID FERNS 



[CH. 



transverse section : while in C.persica (Bory) Mett there is a radial dictyostele 

 much more highly segregated than in these (Marsh, 645). Parallel with this 

 go changes in the bulk of the xylem, and in the increasing proportion of 

 parenchyma that it contains. The petiolar meristele varies also from the 

 primitive type with three endarch protoxylems {C. Fendkri, at base only) 

 to an exarch median protoxylem, which is finally eliminated as in C.gracillima 

 and lanuginosa. Thus anatomically these species suggest a progression in 

 which C. Fendlerixi, the most primitive : it leads from solenostely to confirmed 

 dictyostely (Marsh, Fig. 11, p. 6S0). 



Fig. 642. Cheilanthes S\v. ,-7 = leaf of Ch. fragrans (L.) Webb & Berth. i>=secondary pinnule oi 

 the same with venation and sori, C=Ch. farinosa Kaulf., habit. Z> = primary pinna of Ch. Reg- 

 nelliana Mett. ^=part of a pinnule of the same, with sorus and protective margin. F=Ch. tiiyrio- 

 phylla Desv., part of the blade. {A, -5 after Luerssen : D Rafter Baker, Fl. Brasil: C, -'^ after Diels.) 



