An Illustrated Flora of the Northern United States, Canada and the British Possessions/Hymenophyllaceae

by Nathaniel Lord Britton & Addison Brown

Family 3.   Hymenophyllàceae   Gaud.   in Freyc. Voy. 262.   1826.
Filmy-Fern Family.

Membranaceous, mostly tropical small ferns, with slender often filiform creeping or rarely suberect rootstocks, the leaves usually much divided, the leaf-tissue pellucid, usually of a single layer of cells. Sporanges sessile upon a filiform, usually elongate receptacle, within an urn-shaped or tubular truncate or twolipped marginal indusium, terminal upon the veins; ring complete, transverse, opening vertically.

Two genera, Hymenophyllum and the following, comprising some 450 or more species, abundant in the humid tropics and mainly epiphytic.

1.   Trichómanes   L.   Sp. Pl. 1097.   1753.

Blades entire, pinnatifid or lobed, or several times pinnately divided. Indusium tubular or funnel-shaped, truncate or sometimes broadly two-lipped, the sporanges sessile, mostly upon the lower portion of the slender often exserted receptacle. [Greek, in allusion to the delicate hair-like ultimate segments of some of the species.]

About 210 species, mostly tropical. Besides the following. 3 species occur in the southern United States. Type species: Trichomanes crispum L.

1.  Trichomanes Boschiànum  Sturm. Filmy-fern.   Bristle-fern.   Fig. 18.
Trichomanes Boschianum Sturm; v. d. Bosch.  Ned. Kr. Arch. 5²: 160.   1861. Trichomanes radicans of American writers. Not Sw.
Rootstocks filiform, wiry, tomentose, creeping. Stipes (petioles) ascending, 1′–3′ long, naked or nearly so; leaves 2′–8′ long, 8″–1½″ wide, membranaceous, lanceolate or ovate·lanceolate, 2-3 pinnatifid; pinnae ovate, obtuse, the upper side of the cuneate base parallel with or appressed to the narrowly winged rachis; segments toothed or cut into linear divisions; indusia terminal on short lobes, 1-4 on a pinnule, the mouth slightly 2-lipped; receptacle more or less exserted, bristle-like, bearing the sessile sporanges mostly near the base.
On wet rocks, Kentucky to Florida and Alabama. Also in the West Indies, Mexico, tropical America, Europe, Asia and Africa.  Summer.