Parablechnum

Smith, Alan R. & Kessler, Michael, 2018, Prodromus of a fern flora for Bolivia. XXXIII. Blechnaceae, Phytotaxa 334 (2), pp. 99-117 : 110-111

Key to the Bolivian species of Parablechnum

1 Pinna margins strongly revolute to about halfway from margins to costae; pinna apices obtuse .................................................... 2

– Pinna margins not to moderately revolute; pinna apices acuminate ................................................................................................ 3

2 Pinnae sessile, about 10–15 times longer than wide ......................................................................................................... P. loxense

– Pinnae stalked, about 5 times longer than wide .............................................................................................................. P. reflexum

3 Rachis scales dense, some scales> 5 mm long ................................................................................................................................. 4

– Rachis scales absent to sparse, all scales <5 mm long ..................................................................................................................... 5

4 Pinna bases abruptly truncate; laminar veins deeply sunken abaxially, prominently raised adaxially ................................... P. lima

– Pinna bases cordate; laminar veins not or very slightly sunken abaxially, not raised adaxially ................................ P. squamatum

5 Rhizomes 0.3–0.4 cm wide, blackish, long-creeping .......................................................................................................... P. repens

– Rhizomes 2–4 cm wide, brown, erect, ascending, or short-creeping ............................................................................................... 6

6 Aerophores at pinna bases peg-like, 2–5 mm long; petioles and rachises (at least proximally) atropurpureous .............. P. lechleri

– Aerophores at pinna bases knoblike, to 1 mm long; petioles and rachises stramineous to atropurpureous ..................................... 7

7 Blades with minute, two-celled glandular hairs ...................................................................................................... P. wohlgemuthii

– Blades lacking glandular hairs .......................................................................................................................................................... 8

8 Scales of rachises and costae decidedly dentate (tooth length to 1/3–1/2 of scale width); pinna pairs 20–40 ............... P. smilodon

– Scales of rachises and costae weakly dentate (tooth length <1/5 of scale width); pinna pairs 7–25 ............................................... 9

9 Rhizome scales orange to pale brown, concolorous; pinnae 10–30 × 1.5–4 cm ............................................................................ 10

– Rhizome scales reddish brown to blackish, concolorous or bicolorous with paler margins; pinnae 7–16 × 1–2 cm .................... 12

10 Sterile and fertile leaves weakly dimorphic, the fertile pinnae with broad (several mm) green margins ............ P. monomorphum

– Sterile and fertile leaves strongly dimorphic, the fertile pinnae without or with very narrow (<1mm wide) green margins ........ 11

11 Buds lacking ................................................................................................................................................................... P. cordatum

– Buds (often inconspicuous) present in the axils of some pinnae .................................................................................. P. proliferum

12 Rhizome scales with red-brown centers and pale margins, cells translucent ................................................................................. 13

– Rhizome scales dark reddish brown to blackish, concolorous, cells occluded .............................................................................. 14

13 Rhizome scales 6–10 × 1–2.2 mm; costal scales 1–2 × 0.4–1 mm, entire to erose, reddish brown with slightly paler margins ........ ............................................................................................................................................................................................. P. bicolor – Rhizome scales 14–30 × 2–3 mm; costal scales 0.3–1 × 0.2–0.8, denticulate, tan .............................................. P. cochabambense

14 Costal scales tan, appressed; rhizome scales blackish, entire; rhizomes short, erect .................................................. P. bolivianum

– Costal scales partly dark brown with pale margins, slightly spreading; rhizome scales dark reddish brown, denticulate; rhizomes elongate, creeping to suberect ........................................................................................................................................... P. pazense