596 FILICALES 



these genera are the two first, which were placed apart in the Synopsis 

 Filicum : Dennstaedtia (as Patania} was included in Dicksonia, while 

 Microlepia was included as a section of Davallia. But evidently systematists 

 had reason to know how closely allied these two were, since the synonyms 

 have been numerous. The fact is that Dennstaedtia is not very nearly related 

 to Dicksonia; the form of sorus is different, and the details of the sporangium ; 

 these characters should weigh more strongly than any similarity of habit. 

 On the other hand, Microlepia, while it resembles Dennstaedtia in its sorus, 

 differs in some essential points from Davallia. Certain new facts have 

 confirmed the soundness of Prantl's systematic method of founding the 

 sub-tribe : it will be seen that the Ferns included in it occupy a peculiarly 

 interesting position, as connecting links between the basipetal type of sorus 

 seen in the Dicksonieae, and that of the Davallias. 



MICROLEPIA = {Davallia, Microlepia}. 



This genus includes Ferns with creeping rhizome, on which solitary 

 leaves are borne, which are not articulated at the base. The surfaces bear 

 hairs, not ramenta. The leaves are repeatedly pinnate, and bear sori with 

 the indusium unequally lipped ; the upper lip appears as a continuation of 

 the leaf-surface, the lower lip as a membranous half-cup-shaped outgrowth : 

 the result is that the whole sorus appears to be intra-marginal. 



The sorus has been examined in Microlepia speluncae (L.), Moore, hirta 

 (Kaulf), Presl, strigosa (Thunb.), Presl, and platyphylla (Don), J. Sm. In 

 all these it shows in the main a basipetal succession. This is seen in 

 M. speluncae, in Fig. 332 A, in which the two lips of the indusium appear 

 with the characteristic inequality, the superior lip (s.) having the aspect of 

 a continuation of the leaf-lobe, while the inferior lip (/.) is smaller, and has 

 some similarity in position to the indusium of Cystopteris. The receptacle 

 is conical, but the sporangia are not very numerous, and it is not greatly 

 elongated; it is traversed by a band of tracheides (/;-.). The order of 

 appearance of the sporangia is in a strict basipetal succession, but this is 

 not long maintained. The sporangia themselves are on short, rather thick, 

 three-rowed stalks, and the head shows a slightly oblique form, the peripheral 

 face being the more convex. The annulus is almost longitudinal, but still 

 it shows a slight degree of obliquity, such as will be described below in 

 Dennstaedtia apiifoiia ; the orientation of the sporangia shows a considerable 

 regularity on the Gleicheniaceous type. 



In Microlepia hirta there is general correspondence to M. speluncae as 

 regards structure of the sorus and sporangium, though the succession of 

 sporangia is longer, and the receptacle accordingly more elongated ; but 

 cases occur occasionally in which the strict basipetal succession is hot 

 maintained. One of these is represented in Fig. 332 B, in which there is 

 a larger sporangium at the tetrad stage, and below a small one in which 

 the spore-mother-cells have not yet expanded. Fig. 332 c shows another 



