22 DlCKSONIE-E. 

 (a) Indusium distinctly two-valved. 



132. DICKSONIA, L'Heritier, Sertum Anglicum 30. 



BitAif Tira, Kaulfu* -. Presl; CITLCITA, Presl ; LEPTOPIJSTTBIA, Presl ; 

 CTSTODIUM, J. Smith; DAVALLI^ sp.,Auct.; CmoTiisp.,Auct.; MICEO- 

 LEPI.E sp., Auct. ; PATAIU.S sp., Auct.; NEPHBOLEPIDIS sp., Mettenius. 



Sori involucrately-indusiate, globose or short transverse ob- 

 long, marginal, more or less reflexed ; the receptacles globose or 

 transverse oblong, terminal. Indusium coriaceous, double i.e. 

 two- valved ; the outer or accessory valve formed of a more or 

 less attenuated lobule of the frond, cucullate, sometimes equalling 

 in size, but more frequently larger than the inner valve or proper 

 indusium, which latter, when smaller, is less convex than the 

 outer. Veins simple forked or pinnate, from a central costa ; 

 venules free. 



Fronds coriaceous, usually large decompound, sometimes 

 pinnate, the fertile portions appearing somewhat contracted. 

 Rhizome thick, short, erect, or arborescent ; sometimes (in D, 

 Culcita) decumbent, criniferous. A genus of noble ferns, includ- 

 ing several arborescent species. It is distinguished from Denn- 

 stadtia by the two-valved, not entire cup-shaped, indusium ; and 

 from Cibotiwn by the more or less herbaceous texture of the 

 outer valve of the indusium, which in Dicksonia, is but a par- 

 tially changed lobule of the frond. 



Ex. : D. arborescens, L'Herit. I D. antarctiea, Labitt. 



D. squarrosa, Sw. \ D. Sellowiana, Hook. 



D. eoniifolia, Hook. 

 D. dubia, &aud. 

 D. sorbifolia, Sm. 



D. Culcita, L'Herit, 

 D. Plumieri, Hook 

 D. abrupta, Sory. 



133. DICLISODON, M. (bom ditto, double or two-valved, 

 and odon.) 



Sori involucrately-indusiate, rotundate, extra-marginal, i.e., 

 occupying small projecting marginal teeth ; the receptacles punc- 

 tiform, terminal. Indusium extrorse-marginal, two-valved, flat ; 

 the outer or accessory valve a small rounded herbaceous project- 

 ing lobe of the frond; the inner valve, or proper indusium, 

 membranaceous, larger than the lobe, distinctly reniform affixed 



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