Bower.—Studies in the Phytogeny of the Filicales. VJJ. 51 
Dennstaedtiinae, which is probably its natural place; 1 though Prantl 
regarded the position assigned for Hypolepis as provisional, 2 since he had 
no developmental material at hand. It will therefore be useful to re¬ 
examine the characters upon which the genus is so placed. 
The similarity of character of Dennstaedtia and Hypolepis depends first 
on habit: the creeping rhizome, with relatively long internodes, and ample 
upright-growing leaves of high pinnation and finely cut; the vestiture of 
hairs only; and the numerous sori, each seated in a sinus of the margin. 
Anatomically the rhizomes in both are solenostelic. Gwynne-Vaughan 
has shown the similarity of the vascular system of Dennstaedtia punctiloba 
and apiifolia 3 to those of Hypolepis millefolia , teimifolia , and repens . 4 
Though the latter show some advance in detail on the former, still they 
are less complex than D. adiantoides 5 or rubigin sa , 6 in which a medullary 
system exists. The leaf-trace also comes off undivided, though inter¬ 
ruptions of its continuity, of the nature of perforations, may occur above 
their base, as they do also in the solenostele of some of them. But these 
details do not materially affect the substantial likeness. The chief dis¬ 
tinction lies in the sorus. That of Dennstaedtia is cup-like, and only 
indistinctly two-lipped, while that of Hypolepis , though corresponding in 
position, has only a single lip, viz. the upper or adaxial, which curves more 
or less over the receptacle, and is rather membranous in texture. It has 
been described as ‘ formed out of the reflexed margin 5 . 7 The converse of 
this is probably correct: viz. that it has become the equivalent of the 
margin, though phyletically it is a superficial growth. 
In his excellent analysis of the Hay-scented Fern, Dennstaedtia 
punctilobida (Michx.), More, 8 Prof. Conard has already shown the receptacle 
and the first sporangium to be truly marginal in origin. But in order to 
establish our own comparisons, drawings have been made on the one hand 
of sori of Dennstaedtia dissecta (Sw.), Moore, and on the other of Hypolepis 
higrescens , Hk., and repens (L.), Pr., all from specimens collected in Jamaica. 
Fig* 37, shows in outline from below a pinnule of D. dissecta , with 
its cup-like sori on the anadromic branches of the veins. The vascular 
strand terminates in the receptacle as an expanded mass of tracheides. 
The receptacle is marginal in origin, and the indusial flaps are consequently 
superficial. 9 Their relation is shown in Fig. 37, b , and it is there seen 
that the actual margin bears the first sporangium, while a second less 
advanced is already initiated below, thus indicating a basipetal sequence. 
This was found to be the rule in Microlepia , and it is seen in D. apiifolia ; 10 
but it has been shown that in D . rubiginosa the basipetal succession is 
1 Arb. K. Bot. Gart. Breslau, I. i, p. i6. 2 1 . c., p. 19. 
8 Solenostelic Ferns, II. Ann. of Bot., 1903, PI. XXX, Figs. 1, 2. 4 1 . c., Figs. 4, 5, 6. 
5 1 , c., Fig. 2. e p c>? jr}g # 7 Syn. Fil.j p. 128. 
8 Carnegie Institution, Publication No. 94, Figs. 151, 155, 158. 
8 Cf. Conard, 1 . c., Fig. 151. 10 Land Flora, Figs. 332, 332 bis. 
