FloraOfNewZealand-Ferns-29-BrownseyPerrie-2021-...
Blechnaceae is a medium-sized family found throughout the world, but with the majority of species in the southern hemisphere. There are two main centres of diversity in Central and South America, and in Australasia and the south-west Pacific, with a smaller one in the Malesian region. Species occur most frequently in south temperate regions or in montane to subalpine areas of the tropics.
As interpreted here, Blechnaceae is a family of seven genera and about 265 species, represented in New Zealand by a single genus, Blechnum, with 23 indigenous and two naturalised species. Thirteen species are endemic. Alternative classifications recognise up to 25 genera, with seven indigenous to New Zealand (Austroblechnum, Cranfillia, Diploblechnum, Doodia, Icarus, Lomaria and Parablechnum) and two with introduced species (Austroblechnum, Blechnum). Under this classification Austroblechnum is represented by seven indigenous species, Doodia and Parablechnum by five, Cranfillia by three, and Diploblechnum, Icarus and Lomaria by one species each.
Of the indigenous species, Blechnum chambersii, B. deltoides, B. fluviatile, B. membranaceum, B. minus, B. novae-zelandiae, B. penna-marina, B. procerum and B. triangularifolium are all widespread, albeit scarce or absent in the driest parts of the South Island. Blechnum colensoi, B. discolor and B. nigrum are widespread in the North Island but largely confined to wetter, western parts of the South Island. Blechnum blechnoides and B. durum are both entirely coastal, the former found predominantly on the west coast from Northland to Stewart Island and on the subantarctic islands, and the latter confined to the far south from Fiordland and Southland to the subantarctic islands.
One species, B. montanum, has a predominantly southern distribution, occurring from Mt Pirongia in the North Island to the subantarctic. Three species, Blechnum filiforme, B. fraseri and B. parrisiae, have a mainly northern distribution extending only to the northern South Island, and another three, B. molle, B. norfolkianum and B. zeelandicum, are confined to the North Island. The remaining species have restricted distributions: B. kermadecense occurs only on the Kermadec Islands, and B. neohollandicum is a vagrant species recorded from the northern North Island but is probably no longer extant in New Zealand.
All species of Blechnum in New Zealand are terrestrial except for B. filiforme, which is one of the few high-climbing ferns in the flora. It is distinguished by its often strongly dimorphic fronds, sori that are either continuous, or elongate and discrete, arranged parallel to the costae, and indusia opening inwards towards the costae. Hybrids are known to occur between B. chambersii and B. membranaceum, B. molle and B. parrisiae, and in the B. procerum group (including B. minus, B. montanum, B. novae-zelandiae and B. procerum).
Additional Information
| Field | Value |
|---|---|
| Data last updated | 11 February 2021 |
| Metadata last updated | 14 January 2021 |
| Created | 14 January 2021 |
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