Terrestrial ferns. Rhizomes erect, often forming a short woody trunk covered with persistent stipe bases. Rhizome scales absent. Fronds dimorphic. Stipes glabrous or woolly hairy. Laminae 2-pinnate, coriaceous, opaque, with stomata, deciduous, glabrous or hairy. Sporangia borne on highly modified and reduced laminal segments. Spores trilete, radially symmetrical, tuberculate with tubercles bearing slender echinate processes.
A genus of about 10 species. Phylogenetic analysis of DNA sequences from seven plastid loci by Metzgar et al. (2008) has shown that Osmundastrum is distinct from Osmunda, and that the latter comprises three separate subgenera. A single naturalised species is present in New Zealand (Brownsey in Webb et al. 1988; Brownsey & Smith-Dodsworth 2000), which is easily distinguished from the native species of Todea and Leptopteris by its markedly different fertile and sterile pinnae.
About 10 species, with one very widespread species, another in temperate North America and Eurasia, and the rest in east and south-east Asia. One species fully naturalised in New Zealand.
Category | Number |
---|---|
Exotic: Fully Naturalised | 1 |
Total | 1 |
n = 22 (Kramer 1990).