Scientific Name:
Blechnum L., Sp. Pl. 1077 (1753)
  • = Struthiopteris Scop., Fl. Carniol. 168 (1760)
  • = Lomaria Willd., Mag. Neuesten Entdeck. Gesammten Naturk. Ges. Naturf. Freunde Berlin 3: 160 (1809)
  • = Doodia R.Br., Prodr. Fl. Nov. Holland. 151 (1810)
  • = Stegania R.Br., Prodr. Fl. Nov. Holland. 152 (1810)
  • = Blechnopteris Trevis., Atti Reale Ist. Veneto Sci. Lett. Arti II, 2: 166 (1851)
  • = Mesothema C.Presl, Epimel. Bot. 111 (1851)
  • = Parablechnum C.Presl, Epimel. Bot. 109 (1851)
  • = Spicanta C.Presl, Epimel. Bot. 114 (1851)
  • = Diploblechnum Hayata, Bot. Mag. (Tokyo) 41: 702 (1927)
  • = Austroblechnum Gasper & V.A.O.Dittrich in Gasper et al., Phytotaxa 275: 202 (2016)
  • = Cranfillia Gasper & V.A.O.Dittrich in Gasper et al., Phytotaxa 275: 207 (2016)
  • = Icarus Gasper & Salino in Gasper et al., Phytotaxa 275: 275 (2016)
Type Taxon:
Blechnum occidentale L.
From the Greek blechnon (a fern).
Vernacular Name(s):
hard fern; water fern

Terrestrial, rupestral or climbing ferns (NZ), or rarely epiphytic or aquatic (not NZ). Rhizomes erect or short- to long-creeping, scaly. Rhizome scales non-clathrate, triangular or narrowly triangular, brown or dark brown or sometimes bicolorous with paler margins. Fronds monomorphic to markedly dimorphic. Stipes adaxially sulcate, scaly and sometimes hairy. Laminae entire to 1-pinnate, or rarely up to 2-pinnate, herbaceous or coriaceous or rarely slightly fleshy, scaly and sometimes hairy or rarely glabrous. Veins often free or occasionally anastomosing. Sori discrete or continuous on a vein parallel to the mid-vein or costa, occasionally in two rows (NZ), or rarely acrostichoid (not NZ); receptacles raised or flat; indusia attached to the receptacle and opening towards the costae. Spores monolete; perispores very variable, smooth, papillate, echinate, tuberculate, cristate or verrucate.


As interpreted here, a genus of about 230 species (PPG 1 2016).

Two genera, Blechnum and Doodia, have long been recognised in New Zealand (Cheeseman 1925; Allan 1961; Crookes 1963; Brownsey & Smith-Dodsworth 2000), together with a third, Pteridoblechnum, in Australia (Chambers & Farrant 1998). However, recognition of Doodia and Pteridoblechnum makes Blechnum non-monophyletic (Shepherd et al. 2007; Perrie et al. 2014; Gasper et al. 2017), and the three genera were subsumed into the broadly circumscribed, and readily recognised, Blechnum by Perrie et al. (2014). An alternative proposal by Gasper et al. (2016) subdivided the genus recognised here into 16 separate genera, of which Austroblechnum, Cranfillia, Diploblechnum, Doodia, Icarus, Lomaria and Parablechnum occur naturally in New Zealand.

When interpreted broadly, Blechnum is the second largest fern genus in New Zealand with 23 indigenous species. In addition, two exotic species, B. patersonii and B. punctulatum, have been recognised as casuals (Heenan et al. 2008). Previously, Allan (1961) recognised 15 species in Blechnum and just two in Doodia, with one additional variety. Inclusion of Doodia within a broadly construed Blechnum requires some new names, which have been provided by Christenhusz et al. (2011) and Perrie et al. (2014).

Under the scheme of Gasper et al. (2016), the New Zealand species fall into the following segregates:

Austroblechnum: banksii, colensoi, durum, lanceolatum, membranaceum, norfolkianum, penna-marina (7 species)

Cranfillia: fluviatilis, nigra, deltoides (3 species)

Diploblechnum: fraseri (1 species)

Doodia: aspera, australis, milnei, mollis, squarrosa (5 species)

Icarus: filiformis (1 species)

Lomaria: discolor (1 species)

Parablechnum: minus, montanum, novae-zelandiae, procerum, triangularifolium (5 species)

1Laminae 2-pinnatifid; rachises with a jagged wingfraseri
Laminae 1-pinnatifid to 1-pinnate or rarely 2-pinnate proximally; rachises lacking a jagged wing2
2Veins at least partially anastomosing; sori oblong, discrete or rarely continuous, arranged along the length of each pinna, in 1–2 rows either side of, and parallel to, the costa 3
Veins free; sori continuous along the length of each pinna, in 1 row either side of, and parallel to, the costa 7
3Pinnae stalked in at least the lower half of the rachis; sterile fronds often prostrate and smaller than the fertile fronds; sterile pinnae shorter and broader than the fertile pinnae 4
Pinnae all adnate, or stalked only in lower ⅓ of rachis; fertile and sterile fronds similar; fertile and sterile pinnae similar 5
4Terminal pinna < ⅛ total frond length; rachis hairy molle
Terminal pinna ⅛ to ½ total frond length; rachis scaly but not hairy zeelandicum
5All pinnae, except sometimes the basal pair, adnate to rachis; stipe and rachis bearing tubercles neohollandicum
At least some pinnae above the basal pair stalked; stipe and rachis lacking tubercles 6
6Young fronds tinged pink; rachises and laminae minutely hairy; pinnae up to 80 mm long parrisiae
Young fronds never tinged pink; rachises and laminae sparsely hairy or glabrous; pinnae up to 140 mm long kermadecense
7Sterile laminae pinnate, at least in the lower half, with pinnae sessile or joined to the rachis by short stalks 8
Sterile laminae entire, pinnatifid or with pinnae adnate to the rachis 15
8Rhizomes long-creeping and climbing; juvenile and adult sterile fronds markedly different; fertile fronds formed on plants above ground filiforme
Rhizomes short-creeping or erect, not climbing; juvenile and adult sterile fronds similar; fertile fronds produced on terrestrial plants 9
9Fertile and sterile pinnae <35 mm long; rachises densely scaly fluviatile
Fertile and sterile pinnae >35 mm long, or, if <35 mm long, rachises sparsely scaly 10
10Proximal pinnae on sterile fronds many times shorter than those at mid-lamina; proximal pinnae on fertile fronds reduced to short, sterile lobes 11
Proximal pinnae on sterile fronds rarely < half the length of those at mid-lamina; proximal pinnae on fertile fronds similar to those above, lacking sterile lobes 13
11Longest sterile pinnae up to 38 mm long and 5 mm wide punctulatum
Longest sterile pinnae 10–400 mm long and 6–30 mm wide 12
12Scales on distal stipe, rachis and costae uniformly pale brown; sterile pinnae in 3–27 widely spaced pairs, each 6–18 mm wide; sterile laminae 80–1000 mm long, 20–310 mm wide minus
Scales on distal stipe, rachis and costae pale brown with a conspicuous dark basal spot; sterile pinnae in 7–53 crowded pairs, each 9–30 mm wide; sterile laminae 150–2125 mm long, 65–740 mm wide novae-zelandiae
13Sterile pinnae straight, with acute or obtuse apices, in 1–12 pairs, 10–35 mm wide; scales on distal stipe, rachis and costae often bicolorous but lacking a well-defined dark spot; fertile fronds longer than the sterile procerum
Sterile pinnae often falcate, with acuminate apices, in 5–32 pairs, 7–28 mm wide; scales on distal stipe, rachis and costae with a well-defined dark spot; fertile fronds shorter or about equalling the sterile 14
14Laminae 60–280 mm wide; pinnae 7–24 mm wide, often slightly reduced in length proximally; plants mostly confined to montane or subalpine regions except in the far south montanum
Laminae 90–560 mm wide; pinnae 9–28 mm wide, not reduced in length proximally; plants mostly confined to coastal and lowland regions triangularifolium
15Laminae entire or divided into <12 pairs of pinnae 16
Laminae divided into >12 pairs of pinnae 18
16Margins of sterile laminae bearing red-brown hairs; lowermost pair of sterile pinnae equal to, or larger than, the pair above nigrum
Margins of sterile laminae glabrous; laminae entire, or lowermost pair of sterile pinnae shorter than those above 17
17Two broad wings of lamina tissue formed below the basal pair of pinnae on sterile fronds, basal pairs of tiny flanges absent; longest sterile pinnae 6–32 mm widepatersonii
Broad wings of lamina tissue absent below basal pair of pinnae on sterile fronds, pinnae gradually reducing to tiny discrete flanges; longest sterile pinnae 15–45 mm wide colensoi
18Stipes and rachises densely scaly throughout fluviatile
Stipes and rachises glabrous or bearing only scattered scales, except at the base19
19Rhizomes long-creeping; fertile fronds up to twice as long as sterile penna-marina
Rhizomes erect or short-creeping; fertile fronds shorter, or only a little longer, than sterile 20
20Abaxial lamina surfaces hairy; pinnae in lower half of lamina not becoming shorter proximally, with the lowermost pair directed basiscopically deltoides
Abaxial lamina surfaces lacking hairs; pinnae in lower half of lamina becoming shorter proximally, with the basal ones reduced to tiny flanges, directed laterally 21
21Sterile laminae paler green on abaxial surface; fertile laminae showing a marked transition throughout their length, from fertile pinnae distally to sterile pinnae proximallydiscolor
Sterile laminae similar colour on both surfaces; fertile laminae either bearing only fertile pinna segments, or transitioning to sterile pinnae only near the base of the lamina 22
22Sterile laminae slightly fleshy; sterile pinnae with almost entire margins; plants confined to coastal rock or scrub 23
Sterile laminae not fleshy; sterile pinnae with toothed margins; plants of coastal or inland forest 24
23Sterile laminae 5–40 mm wide; longest fertile pinnae 5–23 mm long; rhizome and stipe scales chestnut-brown, concolorousbanksii
Sterile laminae 22–125 mm wide; longest fertile pinnae 12–68 mm long; rhizome and stipe scales chestnut-brown with black marginsdurum
24Sterile laminae 8–40 mm wide; margins of sterile pinnae coarsely toothed; proximal pinnae in opposite pairs; fertile fronds usually longer than sterilemembranaceum
Sterile laminae 15–250 mm wide; margins of sterile pinnae finely toothed; proximal pinnae alternate; fertile fronds usually shorter than sterile25
25Sterile laminae 80–600 mm long, 15–115 mm wide, red-tinged when young; sterile pinnae in 7–54 pairs, the longest 14–60 mm long, apices acute or rarely obtuse; length:width ratio 4–6.5:1 in sterile laminae, 5–10:1 in fertile laminaechambersii
Sterile laminae 265–700 mm long, 70–250 mm wide, never red-tinged; sterile pinnae in 25–58 pairs, the longest 50–125 mm long, apices acuminate; length:width ratio 3–5:1 in sterile laminae, 2–5:1 in fertile laminae norfolkianum

In New Zealand, species of Blechnum are mostly terrestrial ferns, often with strongly dimorphic fronds, sori that are elongate or continuous parallel to the costae, and indusia that open inwards towards the costae. Spores are particularly variable, from almost smooth to cristate, verrucate and tuberculate (Large & Braggins 1991; Chambers & Farrant 2012, figs 1–2).


Blechnum is a subcosmopolitan genus but is most richly represented in southern temperate regions and in montane to subalpine areas of the tropics. The greatest diversity is in Central and South America with some 80 species (Rolleri & Prada 2006; Zuloaga et al. 2008), and in Australia and the south-west Pacific with almost 70 species (Perrie et al. 2014); seven species in southern Africa (Crouch et al. 2011), 22 in the Malesian region (Chambers & Farrant 2012), 28 in Australia (Chambers & Farrant 1998) and perhaps 35 in the south Pacific; 25 species in New Zealand; 13 endemic, ten indigenous and two casual.

Indigenous (Non-endemic)
Number of species and named hybrids in New Zealand within Blechnum L.
Indigenous (Endemic)15
Indigenous (Non-endemic)10
Exotic: Casual2

Base chromosome numbers of x = 28–37 are known in Blechnum (Kramer et al. 1990).



Incertae Sedis

Lomaria paleacea Potts, New Zealand Country J. 6: 84 (1882)

            Type: Banks Peninsula (not located in AK, CHR, K or WELT – see Brownsey & Perrie 2019).

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