HYPOLEPIS, ETC. 



[CH. 



is probably the correct view, for we shall see that the indusium is by descent 

 a superficial growth which has later become merged into the leaf-margin. 

 Our comparison may start from Deiinstaedtia dissecta (Sw.) Moore, a pinnule 

 of which seen from below shows almost spherical sori, turned obliquely 



Fig. 583. Vascular system q{ Hypolepis repeals, showing the 

 departure of a leaf-trace (Z. 7".) from the solenostele, and the 

 attachment to it of two lateral shoots, the one arising from 

 the basiscopic margin of the leaf-trace {l.sh.), the other from 

 the acroscopic margin (l.s/i' .). (After Gwynne-Vaushan.) 



downwards, and borne each on an anadromic veinlet (Fig. 584, a). The 

 vascular strand terminates in the convex receptacle as an expanded mass 

 of tracheides, and the sorus is enclosed by upper and lower indusial flaps 

 (Fig. 584, c). The lips gape widely, pressed apart by the very numerous 



Fig. 584. a = a pinnule of Dennstaedtia dissecta (Sw.) Moore, seen from below, showing marginal 

 sori on the apex of the anadromic branches of the veins ( x 4). /; = very young sorus, cut in vertical 

 section, showing the marginal receptacle and superficial indusial flaps ( x 150). c= mature sorus in 

 vertical section ( x 35). 



adax = \}s\Q upper indusial flap: abax=i\\Q lower. It will be noted that in h the upper surface is to 

 the left, in c to the right. 



