Blechnum L.

Based on: P.J. Brownsey & L.R. Perrie (2021)

Blechnum chambersii. Plant with sterile fronds forming a suberect rosette, and shorter fertile fronds arising centrally. Image: L.R. Perrie © Leon Perrie CC BY-NC 3.0 NZ

Classification

Class

Polypodiopsida

Subclass

Polypodiidae

Order

Polypodiales Link

Family

Blechnaceae Newman

Nomenclature

Scientific Name:

Blechnum L., Sp. Pl. 1077 (1753)

Synonymy:

= 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.

Etymology:

From the Greek blechnon (a fern).

Vernacular Name(s):

hard fern; water fern

Description

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.

Taxonomy

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)

Key

1	Laminae 2-pinnatifid; rachises with a jagged wing	fraseri
	Laminae 1-pinnatifid to 1-pinnate or rarely 2-pinnate proximally; rachises lacking a jagged wing	2
2	Veins 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
3	Pinnae 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
4	Terminal pinna < ⅛ total frond length; rachis hairy	molle
	Terminal pinna ⅛ to ½ total frond length; rachis scaly but not hairy	zeelandicum
5	All 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
6	Young 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
7	Sterile 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
8	Rhizomes 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
9	Fertile 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
10	Proximal 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
11	Longest 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
12	Scales 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
13	Sterile 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
14	Laminae 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
15	Laminae entire or divided into <12 pairs of pinnae	16
	Laminae divided into >12 pairs of pinnae	18
16	Margins 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
17	Two 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 wide	patersonii
	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
18	Stipes and rachises densely scaly throughout	fluviatile
	Stipes and rachises glabrous or bearing only scattered scales, except at the base	19
19	Rhizomes 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
20	Abaxial 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
21	Sterile laminae paler green on abaxial surface; fertile laminae showing a marked transition throughout their length, from fertile pinnae distally to sterile pinnae proximally	discolor
	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
22	Sterile 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
23	Sterile laminae 5–40 mm wide; longest fertile pinnae 5–23 mm long; rhizome and stipe scales chestnut-brown, concolorous	banksii
	Sterile laminae 22–125 mm wide; longest fertile pinnae 12–68 mm long; rhizome and stipe scales chestnut-brown with black margins	durum
24	Sterile laminae 8–40 mm wide; margins of sterile pinnae coarsely toothed; proximal pinnae in opposite pairs; fertile fronds usually longer than sterile	membranaceum
	Sterile laminae 15–250 mm wide; margins of sterile pinnae finely toothed; proximal pinnae alternate; fertile fronds usually shorter than sterile	25
25	Sterile 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 laminae	chambersii
	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

Recognition

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).

Distribution

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.

Biostatus

Indigenous (Non-endemic)

Number of species and named hybrids in New Zealand within *Blechnum* L.
Category	Number
Indigenous (Endemic)	15
Indigenous (Non-endemic)	10
Exotic: Casual	2
Total	27

Cytology

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

Notes

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).

Bibliography

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