XX XVI] 



LEPTOLEPIA. MONACHOSORUM 



13 



Leptosporangiate Ferns which have actually marginal sori, or can be shown 

 by comparison of early related forms to have been derived from such. This 

 may be held as a justification for devoting a special chapter to Hypolepis: 

 for though we rank it with the Dennstaedtiinae, it is actually in advance of 

 them in certain features. It is a very suggestive type in a Sub-Family that 

 takes its origin from a primitive source, where relatively massive sporangia 

 were in the first instance of marginal position. 



LEPTOLEPIA Mettenius, Kuhn 

 A brief note may here be added on this genus, which was included by Hooker in 

 Davallia {Syn. Fil. p. 91), but was treated by Christ as a section of Microlepia {I.e. p. 308). 

 It comprises two species, both Autralasian : the better known of these is Leptolepia Novae- 

 Zelandiae (Col.) Kuhn. The creeping rhizome is covered with hairs, which are raised 

 slightly from the surface each upon a multicellular cushion. It is traversed by a typical 

 solenostele, with an undivided leaf-trace of wide horse-shoe form : these features are 

 common iox Microlepia (Gwynne-Vaughan, Ann. of Bot. XVli, p. 691, G.-V. slides 845-856). 

 The sori are terminal on an abbreviated lateral vein : but the indusium, unlike that of 

 Microlepia and Davallia., is attached only to the vein of the pinnule, and is free upwards, 

 while its margin is eroded into tatters (see Fig. 588, A.,B., p. 16). The sorus has not been 

 examined developmentally. These characters collectively point to a place in the Denn- 

 staedtiinae of Prantl, rather than with Davallia., which bears scales and has a highly dis- 

 integrated leaf-trace. Leptolepia appears to be even more primitive than Microlepia., which 

 it most closely resembles (see Vol. ll, p. 274). 



MONACHOSORUM Kze. 

 Another example of elimination of the inner indusium is presented by the genus 

 Monachosoruni, which includes two Asiatic species : of these the better known is M. digi- 

 tatum (B. i) Kuhn. After wide vicissitudes of 

 classification, and having received seven 

 generic synonyms, it has been located by 

 Dials as a substantive genus near to Denn- 

 staedtia., which it resembles in habit, and 

 particularly in the presence of bulbils in the 

 axils of the primary pinnae. Detailed exami- 

 nation also supports this comparison (Studies 

 VII, Ann. of Bot. xxxil, p. 56). The thin 

 ascending axis bears laxly crowded leaves, 

 with ferrugineous hairs, not scales. The rhi- 

 zome contains a dictyostele not far removed 

 from solenostely : the leaf-trace originates 

 undivided as in Dennstaedtia., but it divides 

 at once into two straps. The sorus is super- 

 ficial without any indusium, and it is seated at 

 or very near to the slightly enlarged end of 

 a vein (Fig.587 bis). The sporangia are almost 

 simultaneous in origin, while the annulus is 

 interrupted at the insertion of the stalk. These 

 characters, together with the anatomy and the 

 presence of hairs not scales, justify the position Fig. 587 bis. Pinnule oi Monachosorum subdigi- 



assigned bv Diels in proximity to Z?6V/;/^A?^^//.^, ^f "'«' ^f " ^''T'^'J^I' "^'-^ ^%t '"'' ^""'"^ 



" ', , , • , • r close to the ends of the veins. The sporangia 



as a type that has become ex-indusiate, after have been removed from those on the right. 



the manner of Hypolepis. ( x ro.) 



