. Our native ferns and their allies [microform] : with synoptical descriptions of the American Pteridophyta north of Mexico . Ferns; Ferns; Pteridophyta; Fougères; ; . name from the delicate, hood-like indusium which is attached by its broad base on the inner side of the roundish sorus and partly under it. Later this is thrown back and withers away. The veins are free, and the fronds have the aspect of species of Aspidmm, but are usually more delicate in texture. 51. Onoclea.âThis genus contains two quite dissimilar species, which until recently have been separated into two genera by America
. Our native ferns and their allies [microform] : with synoptical descriptions of the American Pteridophyta north of Mexico . Ferns; Ferns; Pteridophyta; Fougères; ; . name from the delicate, hood-like indusium which is attached by its broad base on the inner side of the roundish sorus and partly under it. Later this is thrown back and withers away. The veins are free, and the fronds have the aspect of species of Aspidmm, but are usually more delicate in texture. 51. Onoclea.âThis genus contains two quite dissimilar species, which until recently have been separated into two genera by American botanists. Both have dimorphous fronds, the margin of the contracted fertile frond being strongly revo- lute, and concealing the fruit. 0. striithioptcris has necklace- shaped pinnae, crowded confluent sori, and free and simple veins. O. sensibilis has panicled berry-shaped pinnules and co- piously anastomosing veins. 52. Woodsia (Fig. 9) has round- ish sori borne on the back of the veins, with the indusia attached be- neatli the sporangia and flat and open, or early bursting at the top into ir- regular laciniae or lobes. In § Eu- wooDSlAthe indusia are flat and open Fig gâiroodsia ohtusa from an early stage, with their cleft '^^^t^.^Z ^ and ciliate margins concealed under inferior indusia. the sori. In ^! Hypopeltis the indusium is more conspicuous and encloses the sporangium at first, but soon bursts at the top, forming several jagged lobes. 53. Dicksonia.âIn this genus the small globular sorus is borne in an elevated, globular receptacle, and enclosed in an in- ferior, membranous, cup-shaped indusium. The veins are al- ways free. 54. Trichomanes (Fig. 10) has sessile sporangia borne on a filiform receptacle at the summit of a vein. The indusia are tubrlar or funnel- shaped, with an expanded and often somewhat two-lipped mouth. 55. Lygodium.âIn our species of climbing-fern the fructification is P"'f'- ^o.~Trichowanes radi- 1 .. J /⢠1 , . , "^"-^
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