Scientific Name:
Diplazium Sw., J. Bot. (Schrader) 1800(2): 61 (1801)
Type Taxon:
Diplazium plantagineum (L.) Sw. = Diplazium plantaginifolium (L.) Urb.
From the Greek diplasios (double), a reference to the paired sori in these ferns.

Terrestrial or rupestral ferns. Rhizomes erect or creeping, scaly. Rhizome scales non-clathrate, narrowly ovate or ovate. Stipes adaxially grooved, scaly, sometimes spiny (not NZ). Laminae 2-pinnate to 3-pinnate-pinnatifid (NZ) or entire or 4-pinnate (not NZ), herbaceous (NZ) or coriaceous (not NZ), scaly, groove of rachis U-shaped and continuous with grooves of pinna midribs. Veins free or rarely anastomosing. Sori elongated along veins and either single or arranged back-to-back; indusia same shape as the sori, opening away from the vein, margins entire to laciniate. Spores monolete, perispores rugose.


A genus of about 350 species (PPG 1 2016), badly in need of monographic study (Kramer 1990) and probably paraphyletic (Wang et al. 2003). Diplazium and allied genera in Japan were more clearly defined by Kato (1977), and some 86 species were treated by Wang et al. (2013) for the Flora of China.

Allan (1961) included the sole indigenous New Zealand species in Athyrium.

1Veins anastomosing; secondary pinnae lobed less than halfway to midrib; roots producing young plants from vegetative budsesculentum
Veins free; secondary pinnae usually lobed halfway or more to midrib; roots not producing young plants from vegetative buds2
2Rhizome erect; laminae 2-pinnate-pinnatifid to 3-pinnate-pinnatifid; tertiary segments 5–38 mm long, 2–12 mm wide, serrate or divided almost to midrib, apices acute or obtuseaustrale
Rhizome creeping; laminae 2-pinnate to 2-pinnate-pinnatifid; tertiary segments 8–11 mm long, 4–5 mm wide, entire or shallowly toothed, apices truncate or roundednipponicum

In New Zealand, Diplazium can be recognised by its 2-pinnate to 3-pinnate-pinnatifid fronds bearing scales, the presence of a U-shaped groove on the adaxial surface of the rachis that is continuous with the grooves of the pinna costae, sori that are linear and arranged singly or back-to-back along the veins, and rugose spores (Large & Braggins 1991).


Worldwide, but mainly in the tropics and subtropics, with a few species extending locally into temperate regions; two species in southern Africa (Crouch et al. 2011), 86 in China (Wang et al. 2013), 10 in Australia (Jones 1998), c. 20 in the Pacific and three indigenous to Hawai‘i (Palmer 2003). One non-endemic and two naturalised species in New Zealand.

Indigenous (Non-endemic)
Number of species in New Zealand within Diplazium Sw.
Indigenous (Non-endemic)1
Exotic: Casual2

The base chromosome number in Diplazium is x = 40 or 41 (Kramer 1990).

Brownsey, P.J.; Perrie, L.R. 2018: Athyriaceae. In: Breitwieser, I.; Wilton, A.D. (ed.) Flora of New Zealand — Ferns and Lycophytes. Fascicle 24. Manaaki Whenua Press, Lincoln.
Christenhusz, M.J.M.; Zhang, X.-C.; Schneider, H. 2011: A linear sequence of extant families and genera of lycophytes and ferns. Phytotaxa 19: 7–54.
Crouch, N.R.; Klopper, R.R.; Burrows, J.E.; Burrows, S.M. 2011: Ferns of southern Africa. A comprehensive guide. Struik Nature, Cape Town.
Jones, D.L. 1998: Athyriaceae. In: Flora of Australia. Vol. 48. 418–429.
Kato, M. 1977: Classification of Athyrium and allied genera of Japan. Botanical Magazine (Tokyo) 90: 23–40.
Kramer, K.U. 1990: Dryopteridaceae. In: Kramer, K.U.; Green, P.S. Pteridophytes and gymnosperms. Vol. 1. In: Kubitzki, K. (ed.) The Families and Genera of Vascular Plants. Springer-Verlag, Berlin.
Kramer, K.U.; Green, P.S. 1990: Pteridophytes and gymnosperms. Kubitzki, K. (ed.) The Families and Genera of Vascular Plants. Vol. 1. Springer-Verlag, Berlin.
Large, M.F.; Braggins, J.E. 1991: Spore atlas of New Zealand ferns and fern allies. SIR Publishing, Wellington.
Palmer, D.D. 2003: Hawai‘i’s ferns and fern allies. University of Hawai‘i Press, Honolulu.
PPG 1 2016: A community-derived classification for extant lycophytes. Journal of Systematics and Evolution 54(6): 563–603.
Swartz, O.P. 1801: Genera et species filicum ordine systematico redactarum. Journal für die Botanik (Schrader) 1800(2): 1–120.
Wang, M.-L.; Chen, Z.-D.; Zhang, X.-C.; Lu, S.-G.; Zhao, G.-F. 2003: Phylogeny of the Athyriaceae: evidence from chloroplast trnL-F region sequences. Acta Phytotaxonomica Sinica 41: 416–426.
Wang, Z.; He, Z.; Kato, M. 2013: Athyriaceae. In: Zhengyi, W.; Raven, P.H.; Deyuan, H. (ed.) Flora of China. Lycopodiaceae through Polypodiaceae. Vol. 2–3. Science Press, Beijing.