44 Charles E. Bcsscy 



Class 21. LEPTOSPORANGIATAE. Sporangia developed 

 from superficial cells. 



Order Filicales. Spores of one kind ; sporangia mostly with 

 an annulus (ring) ; gametophytes monoecious, foliose. 



Family 4. Osmundaceae. Sporangia globose, mostly stalked, 

 with but a trace of a ring, splitting vertically. Osuiunda. (Pf. 

 1,4,372.) 



Family 5. Schizaeaceae. Sporangia ovate or subglobose, ses- 

 sile, with an apical horizontal ring, splitting vertically. Schi.zaea, 

 Lygodium. (Pf. I, 4, 356.) 



Family 6. Gleicheniaceae. Sporangia globose, sessile, with a 

 horizontal ring, splitting vertically. Gleichcnia. (Pf. I, 4, 350.) 



Family 7. Matoniaceae. Sporangia compressed, sessile, or 

 short-stalked, with an oblique ring, splitting obliqueh'. Matonia. 



(Pf. I, 4, 343-) 



Family 8. Parkeriaceae. Sporangia globose, sessile with a 

 vertical ring; splitting transversely. Aquatic ferns natives of 

 the tropics. Ccratoptcris. (Pf. I, 4, 339.) 



Family 9. Cyatheaceae. Sporangia compressed, sessile on a 

 low involucrate receptacle on the leaf surface ; ring, vertical or 

 oblique, splitting transverselv. Dicksonia, Cyathca, Alsophila. 



(Pf.I,4, 113.) 



Family 10. Hymenophyllaceae. Sporangia compressed, ses- 

 sile upon an elongated involucrated, marginial receptacle ; ring 

 horizontal or oblique, splitting vertically. Hymenophyllnrn, 

 Trichomancs. (Pf. I, 4, 91.) 



Family 11. Polypodiaceae. Sporangia compressed, mostly 

 stalked, collected into sori, which are often covered or sur- 

 rounded by an involucre (indusium) ; ring vertical, splitting 

 transversely. Polypodinm, Asplciiiiini, NcpJirodiiiiii, Adiantuiii, 

 Ptcridium. (Pf. I, 4, 139.) 



Order Hydropteridales. Spores of two kinds, microspores 

 and nlegaspores; sporangia without an annulus, male gameto- 

 phytes one-celled, minute ; female gametophytes larger, many- 

 celled, but little larger than the megaspore. 



Family 12. Marsiliaceae. Perennial plants rooted in the mud 



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