Hymenophyllaceae

Kessler, Michael & Smith, Alan R., 2017, Prodromus of a fern flora for Bolivia. X. Hymenophyllaceae, Phytotaxa 328 (3), pp. 201-226 : 202-203

Key to the Bolivian Genera and Subgenera of Hymenophyllaceae

1 Involucres bivalvate (clam-shaped), lips not flared; receptacles usually not exserted; rhizomes nearly glabrous or sparsely covered with light-colored hairs ........................................................................................................................................... Hymenophyllum

– Involucres tubular or conical, sometimes with flared lips; receptacles usually exserted; rhizomes usually covered with reddish or dark brown hairs ............................................................................................................................................................................... 2

2 False veins (unconnected to subtending axes) present between the true veins; fronds small, usually less than 5 cm long; blades entire to pinnatifid or sometimes bipinnatifid; rhizomes long-creeping; roots absent or replaced by root-like shoots ...................... .................................................................................................................................................................................. Didymoglossum

– False veins usually absent; fronds usually more than 5 cm long, often much larger; blades usually pinnate-pinnatifid or more dissected, to 5-pinnate; rhizomes long- to short-creeping or suberect or erect; roots present or absent (replaced by dark, rhizoidal hairs) ................................................................................................................................................................................................. 3

3 Rhizomes long-creeping, narrow (ca. 0.2–0.3 mm diam.); roots present or absent; plants epiphytic (occasionally on rocks); fronds generally small, 2–8 cm long ............................................................................................................................................................ 4

– Rhizomes long-creeping, short-creeping, suberect, or erect, generally thicker (to 2 mm diam.); roots present; plants terrestrial, epipetric, or sometimes hemiepiphytes and climbing trees; fronds generally larger, more than 8 cm long .................................... 5

4 Rhizomes beset with dense, blackish rhizoids (dark hairs; true roots absent), these also sometimes present along the petiolar bases and on winged laminar margins on petioles; blades (when dried) with folds parallel to segment margins ............... Crepidomanes

– Rhizomes lacking dense blackish rhizoids, roots relatively few, blackish rhizoids also lacking from petiolar bases and laminar tissue along petioles; blades (when dried) planar, lacking folds ................................................................................. Polyphlebium

5 Laminar margins bearing hyaline or light brown hairs, these simple or clustered and seemingly forked or stellate at bases; plants terrestrial or epipetric ................................................................................................................... Trichomanes subg. Trichomanes

– Laminar margins entire, lacking hairs; plants terrestrial or hemiepiphytic ...................................................................................... 6

6 Rhizomes long-creeping and hemiepiphytic (climbing) on trees, cordlike or twining, 1–2 mm diam. ........................................... 7

– Rhizomes suberect to erect, not climbing, not cordlike, ca. 2 mm diam. ......................................................................................... 8

7 Rhizomes to 1 mm thick; blades entire to deeply pinnatifid or 1-pinnate with the pinnae shallowly toothed or lobed; petioles lacking or nearly so (blades ± sessile) ................................................................................................. Trichomanes subg. Lacostea

– Rhizomes mostly 1–2 mm thick; blades 1–3-pinnate-pinnatifid; petioles evident ................................................... Vandenboschia

8 Fronds dimorphic, the fertile blades entire, the sterile pinnatifid; sterile blades often ending in a flagelliform tip, rooting or producing buds .......................................................................................................................................... Trichomanes subg. Feea

– Fronds monomorphic, 1-pinnate or more divided; blades ending in flagelliform tips or not .......................................................... 9

9 Blades 1-pinnate, less often pinnate-pinnatifid, usually lanceolate or narrowly deltate .............. Trichomanes subg. Trichomanes

– Blades 2–4-pinnatifid, or 2–4-pinnate-pinnatifid, deltate (lowest pinnae the largest) ................................................................... 10

10 Rhizomes short-creeping to suberect, to 2 mm diam; laminar tissue one cell thick; laminae green, not iridescent when living, drying dark greenish ..................................................................................................................................................... Abrodictyum

– Rhizomes erect or ascending, robust (4–15 mm), robust; laminar tissue three cells thick; laminae bluish green and iridescent when living, drying blackish ................................................................................................................... Trichomanes subg. Davalliopsis