Wilson's filmy fern noun1 •Hymenophyllum wilsonii, a fern in the family Hymenophyllaceae, the filmy ferns.Here it was that the Lastrea Foenisecii was growing in such luxuriance; and in the very cave of which it was the gate keeper I found Wilson's Filmy-Fern, clothing the moist sides as a curtain. — 1864
