Blechnum

Smith, Alan R. & Kessler, Michael, 2018, Prodromus of a fern flora for Bolivia. XXXIII. Blechnaceae, Phytotaxa 334 (2), pp. 99-117 : 102-103

Key to the Bolivian species of Blechnum

1 Blades simple or with 1–2 basal lobes ............................................................................................................................ B. lanceola

– Blades pinnate with (1)2–55 pinna pairs .......................................................................................................................................... 2

2 Blades with (1)2–5(7) pinna pairs; terminal pinnae 2–5 times as long as the lateral pinnae ............................................. B. gracile

– Blades with 5–55 pinna pairs; terminal pinnae to 2(3) times as long as the lateral pinnae .............................................................. 3

3 Blades proximally gradually attenuate, the lowermost pinnae <1/2 the length of the middle pinnae ............................................. 4

– Blades proximally truncate or abruptly reduced, the lowermost pinnae>1/2 the length of the middle pinnae ............................... 7

4 Pinnae free, except at blade apices, usually auriculate on both sides of bases; pinna apices mucronate ......................... B. australe

– Pinnae partly or fully adnate, not or only acroscopically auriculate; pinna apices acute ................................................................. 5

5 Petioles 0–6 cm long; lowermost pinnae <5 mm long, equilateral, triangular or semicircular, broadly adnate; leaves usually 5–25 cm long ...................................................................................................................................................................... B. asplenioides

– Petioles> 4 cm long; lowermost pinnae> 5 mm long, lobed acroscopically and narrowed basiscopically; leaves usually 15–50 cm long ................................................................................................................................................................................................... 6

6 Blades glabrous or hairy abaxially; rachises with scattered scales; rhizome scales bicolorous; petiole scales uniformly pale brown; petioles 1/3–1/10 of total leaf length ....................................................................................................................... B. polypodioides

– Blades densely hairy on both surfaces; rachises lacking scales; rhizome scales uniformly dark brown; petiole scales bicolorous; petioles ca. 1/2 of the leaf length ............................................................................................................................... B. tomentosum

7 Rachises abaxially hairy ................................................................................................................................................................... 8

– Rachises abaxially glabrous ........................................................................................................................................................... 10

8 Rhizome scales 0.5–1 mm long; rhizome scale cells opaque .................................................................................... B. malacothrix

– Rhizome scales 1–2 mm long; rhizome scale cells translucent ........................................................................................................ 9

9 Pinna pairs (19–)23–40 ....................................................................................................................................... B. appendiculatum

– Pinna pairs 9–17(–22) .................................................................................................................................................. B. laevigatum

10 Pinna pairs 30–55; rhizomes and stolons shiny black; pinnae short-stalked to sessile throughout blade length; scales of rhizomes, petioles, and costae denticulate ............................................................................................................................... B. anthracinum

– Pinna pairs 5–40; rhizomes and stolons brown, dull; pinnae adnate and confluent distally; scales entire .................................... 11

11 Petioles <0.5(–1) mm thick; leaves <12(–20) cm long ................................................................................................. B. gracilipes

– Petioles 1–2 mm thick; leaves 20–80 cm long ............................................................................................................................... 12

12 Blades lanceolate, with the middle pinnae the longest; pinna pairs (19–)23–40 ............................................... B. appendiculatum

– Blades broadly triangular or broadly deltate, with the basal pinnae the longest; pinna pairs 12–25(–30) ................ B. occidentale