Trichomanes

Kessler, Michael & Smith, Alan R., 2017, Prodromus of a fern flora for Bolivia. X. Hymenophyllaceae, Phytotaxa 328 (3), pp. 201-226 : 219-220

Key to the Bolivian species of Trichomanes

1 Plants hemiepiphytic; rhizomes long-creeping up small trees; subg. Lacostea ............................................................................... 2

– Plants terrestrial; rhizomes decumbent, suberect, or erect ............................................................................................................... 3

2 Leaves tightly appressed to the tree trunks; blades pinnate to pinnate-pinnatifid ............................................................ T. ankersii

– Leaves arching from tree trunks; blades subentire to shallowly toothed or lacerate ...................................................... T. tanaicum

3 Fronds large, to 60 × 36 cm; roots numerous, robust, to 1 mm thick or more; blades more than one cell thick; subg. Davalliopsis ............................................................................................................................................................................................ T. elegans

– Fronds usually less than 40 × 15 cm; roots numerous to few, filamentous, <0.5 mm thick; laminar tissue 1 cell thick ................ 4

4 Blades with stellate hairs on the veins; subg. Trichomanes ............................................................................................................. 5

– Blades glabrous or with simple hairs ................................................................................................................................................ 6

5 Sori usually 1 per pinna, rarely 2–3; involucres (1) 1.5–2.5 mm wide ...................................................................... T. anadromum

– Sori 1–4 per pinna; involucres to 1.5 mm wide ....................................................................................................... T. polypodioides

6 Leaves strongly dimorphic, the fertile ones longer and narrower than the sterile ones; subg. Feea ............................................... 7

– Leaves monomorphic; subg. Trichomanes ....................................................................................................................................... 8

7 Wings between sinuses and midribs 2–3 mm wide; 5–8 veins running from midribs into each segment ................. T. diversifrons

– Wings between sinuses and midribs 1–2 mm wide; 2–4 veins running from midribs into each segment ........................... T. trollii

8 Blades entire or each abruptly ending in a conform apical segment, or rachises extended, flagelliform and with proliferous apices; involucres fully exserted from segment margins, often stalked; blades glabrous ............................................................................ 9

– Blades each gradually reduced to a pinnatifid apex, rachises not elongate or proliferous; involucres at least partly immersed in blade tissue, laterally fully or partly winged; blades usually hairy ................................................................................................ 11

9 Blades entire, linear ............................................................................................................................................................ T. vittaria

– Blades pinnate, ovate or deltate ...................................................................................................................................................... 10

10 False veins rare or lacking; marginal veins faint and discontinuous; pinna margins usually obtusely serrate .. T. hostmannianum

– False veins abundant perpendicular to the true veins; marginal veins strong, continuous; pinna margins sharply serrate to spinulose ......................................................................................................................................................................... T. pinnatum

11 Pinnae regularly and deeply lobed to pinnatisect; blades partly to completely covered by hairs ....................................... T. lucens

– Pinnae entire to serrate or crenate; blades sparsely to moderately hairy ........................................................................................ 12

12 Hairs on rachises abaxially each with 1–4 cells and a bulbous and usually darker basal cell ...................................... T. delicatum

– Hairs on rachises abaxially each with 2–8-celled hairs and lacking a bulbous, darkened basal cell (basal cell may be slightly wider than other cells) .............................................................................................................................................................................. 13

13 Hairs on rachises abaxially mostly dark brown or blackish, stout, rigid, terete at the base ......................................... T. plumosum

– Hairs on rachises abaxially tawny to orange, delicate, tortuous, the cells flattened ...................................................................... 14

14 Petioles winged (sometimes very narrowly) at least in distal 1/3 ................................................................................... T. accedens

– Petioles not winged, but pinnae sometimes slightly decurrent on the petioles .............................................................................. 15

15 Rachis hairs each 1–3 cells long above basal cell; leaves 5–15 cm long ............................................................... T. vandenboschii

– Rachis hairs 1- to 8-celled above basal cell; leaves (10) 15–50 cm long ........................................................................................ 16

16 Leaves erect, linear to narrowly lanceolate, 15–55 cm long .......................................................................................... T. cristatum

– Leaves arched, deltate to lanceolate, 4–25 cm long ......................................................................................................... T. pilosum