50 Bower.—Studies in the Phytogeny of the Fiticates. VII . 
Hypolepis , Bernh. 
The fact now shown that either the upper indusium (Dictyoxiphium) 
or the lower (Pteris) of the two-lipped sorus may be abortive, raises the 
question whether in any other genera systematically associated with the 
Pterideae there is reason to believe that a similar abortion of the indusium 
has occurred. It seems probable that Hypolepis may best be interpreted 
in this way. This genus has been variously treated by systematists. Presl 1 
places it with Lonchitis , and close to Cheilanthes . Hooker 2 assigns to it 
a similar place. Christ 3 associates it with Phegopteris , and especially with 
Phegopteris pimctata (Thunbg.), Bedd. Diels places it in his Pterideae- 
Cheilanthinae, in near relation to Cheilanthes and Llaveap and in this 
Christensen follows him. 5 In all of these decisions it appears that the chief 
weight of the comparison has been laid upon the sorus, .with its single, 
marginal indusium, and its usually subglobose form. 
But Sir William Hooker 6 discusses the habit of these plants also, as 
bearing upon their systematic position. He points out how Presl in his 
4 Tentamen’ limits the genus to those species corresponding to the Microlepia 
group of Dicksonia , and that John Smith adopted the same view. The 
latter observes that 4 this genus is formed of a group of species characterized 
by their large decompound fronds, which arise from a lengthened creeping 
rhizoma similar in habit to some of the large-fronded species of Poly- 
podinm , 7 and differing from them only in the soriferous crenule being 
altered in texture and reflexed, and therefore not distinct in that respect 
from Cheilanthes ; but their whole habit naturally indicates them to be 
a distinct group from the species which I retain as true Cheila 7 ithes\ If 
those who followed had given more attention to the habit-characters, 
Hypolepis might have sooner arrived at some more fixed systematic position. 
Evidently Diels was dissatisfied with its being placed among the Cheilan- 
thinae, for he remarks 8 that Hypolepis has in habit little in common with 
the other types of this series. To us, who now realize that a very similar 
soral structure may arise along distinct phyletic lines, the habit-character 
acquires additional value. In the present case it is possible that the sorus 
of Hypolepis may have come from some Dicksonioid-Davallioid source, by 
abortion of the inner indusium, while that of Cheilanthes may have been 
uni-indusiate from the first. In which case Hypolepis would be detached 
from the superficial comparison with Cheilanthes . Already Kuhn (1882), 
and later Prantl (1892), had placed Hypolepis with Dennstaedtia , Microlepia , 
Leptolepia , and less certainly Saccoloma , in the newly erected group of the 
1 Tentamen, p. 161, 2 Syn. Fil.,p. 128. 3 Farnkrauter, p. 278. 
4 l.c., p. 277. 5 Index, p. xlii. 6 Sp. Fil, vol. ii, p. 59. 
7 This is clearly an allusion to types such as Polypodiumpunctatum, Thunbg., the relation to 
which will be considered later. 
8 l.c., p. 277. 
