Biosystematics of the cryptogamic flora of New Zealand: Pteridophytes

Abstract

With 189 native and 22 adventive species, pteridophytes are a numerically small but economically and ecologically important component of the New Zealand flora. Taxonomically they arc well known but, following several major revisions and many nomenclatural changes in the last 20 years, there is a need for a new Flora treatment. A more expansive style of Flora including a greater range of information and illustrations for both native and adventive taxa is contemplated. The evidence for hybridisation amongst New Zealand ferns is outlined and a comparison with Cockayne & Allan's list suggests that its extent may be greater than they suspected. Most fern hybrids, with the notable exception of those in Blechnum, appear to be effectively sterile. Chromosome counts have been obtained for about 75% of native species of which 54% are polyploid, a figure comparable with other temperate floras, but only 2% are apomictic. Chemotaxonomy of New Zealand ferns is still in its infancy but can be expected to provide real assistance in subdividing some large families of ferns, especially if combined with morphological and cytological analysis. New Zealand pteridology is now at the point where purely taxonomic investigations are likely to give way gradually to the study of more complex biosystematic problems.

Keywords:

• apomixis
• biosystematics
• chemotaxonomy
• chromosome numbers
• cytology
• ferns
• Flora treatment
• hybridism
• New Zealand: pteridophytes
• taxonomy