Classification
 Subordinate Taxa
 Nomenclature
Scientific Name:
Dennstaedtia Bernh., J. Bot. (Schrader) 1800(2): 124, t. 1(3) (1801)
Type Taxon:
Dennstaedtia flaccida (G.Forst.) Bernh.
Etymology:
Named in honour of the German physician and botanist August Wilhelm Dennstedt (1776–1826), surname sometimes spelled Dennstaedt, director of the Belvedere garden near Weimar.
 Description

Terrestrial ferns. Rhizomes short- (not NZ) to long-creeping (NZ), bearing yellow to red multicellular hairs. Fronds monomorphic. Stipes hairy or occasionally spiny (not NZ). Laminae 3–4-pinnate (NZ) or rarely 1–2-pinnate (not NZ), herbaceous (NZ) or coriaceous (not NZ), bearing non-glandular hairs; primary pinnae stalked, lacking basal pinnule-like stipules. Veins free. Sori round (NZ) or broader than long (not NZ), on a slightly raised receptacle, marginal; paraphyses present or absent. Indusia cup-shaped or slightly bivalvate, formed from a true inner indusium and outer modified inrolled lamina flap, attached at base. Spores trilete, tuberculate to verrucate or coarsely ridged or reticulate.

 Taxonomy

The taxonomy of Dennstaedtia has been revised in America (Tryon 1960; Tryon & Tryon 1982) but is inadequately studied in the Old World. The genus is closely related to, and often difficult to distinguish from, Microlepia. It is also not monophyletic, with two distinct clades identified (Schuettpelz & Pryer 2007; Perrie et al. 2015), one of them closely related to Microlepia. Perrie et al. (2015) also noted that one clade had chromosome numbers based on x = 46 or 47, while the other had counts based on x = 30, 31, 32, 33, or 34.

 Recognition

In New Zealand, Dennstaedtia can be recognised by its creeping rhizomes, highly divided laminae bearing non-glandular hairs, more or less round marginal sori, and cup-shaped or bivalvate indusia.

 Distribution

A genus of about 70 species (PPG 1 2016) in tropical and temperate regions of the Americas, Asia, Australia, and the Pacific (Brownsey 1998); 12 species in the Americas (Tryon 1960; Tryon & Tryon 1982), one in Africa (Roux 2009), eight in China (Yan et al. 2013), 15 in the Philippines (Copeland 1958), 12 in New Guinea (Copeland 1950), one in Australia (Brownsey 1998), and about eight in the Pacific. The Australian species occurs as a casual in New Zealand.

 Biostatus
Exotic
Number of species in New Zealand within Dennstaedtia Bernh.
CategoryNumber
Exotic: Casual1
Total1
 Bibliography
Bernhardi, J.J. 1801: Tentamen alterum filices in genera redigenda. Journal für die Botanik (Schrader) 1800(2): 121–136.
Brownsey, P.J. 1998: Dennstaedtiaceae. In: Flora of Australia. Vol. 48. 214–228.
Brownsey, P.J.; Perrie, L.R. 2018: Dennstaedtiaceae. In: Breitwieser, I.; Wilton, A.D. (ed.) Flora of New Zealand — Ferns and Lycophytes. Fascicle 19. 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.
Copeland, E.B. 1950: Pteridaceae of New Guinea. Philippine Journal of Science 78: 5–41.
Copeland, E.B. 1958: Fern flora of the Philippines. Vol. 1. Bureau of Printing, Manila.
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.
Perrie, L.R.; Shepherd, L.D.; Brownsey, P.J. 2015: An expanded phylogeny of the Dennstaedtiaceae ferns: Oenotrichia falls within a non-monophyletic Dennstaedtia, and Saccoloma is polyphyletic. Australian Systematic Botany 28: 256–264.
PPG 1 2016: A community-derived classification for extant lycophytes. Journal of Systematics and Evolution 54(6): 563–603.
Roux, J.P. 2009: Synopsis of the Lycopodiophyta and Pteridophyta of Africa, Madagascar and neighbouring islands. Strelitzia 23: 1–296.
Schuettpelz, E.; Pryer, K.M. 2007: Fern phylogeny inferred from 400 leptosporangiate species and three plastid genes. Taxon 56: 1037–1050.
Smith, A.R.; Pryer, K.M.; Schuettpelz, E.; Korall, P.; Schneider, H.; Wolf, P.G. 2006: A classification for extant ferns. Taxon 55(3): 705–731.
Tryon, R.M. 1960: A review of the genus Dennstaedtia in America. Contributions from the Gray Herbarium of Harvard University 187: 23–52.
Tryon, R.M.; Tryon, A.F. 1982: Ferns and allied plants. Springer-Verlag, New York.
Yan, Y.; Qi, X.; Liao, W.; Xing, F.; Ding, M.; Wang, F.; Zhang, X.; Wu, Z.; Serizawa, S.; Prado, J.; Funston, A.M.; Gilbert, M.G.; Nooteboom, H.P. 2013: Dennstaedtiaceae. In: Zhengyi, W.; Raven, P.H.; Deyuan, H. (ed.) Flora of China. Lycopodiaceae through Polypodiaceae. Vol. 2–3. Science Press, Beijing.