FloraOfNewZealand-Ferns-25-BrownseyPerrie-2018-...
The medium-sized, cosmopolitan family Isoetaceae includes the single genus Isoetes which has traditionally been represented in New Zealand by two species, I. alpina and I. kirkii. Despite considerable morphological and molecular investigation over the last 40 years, there is no clear evidence as to whether this is correct, or whether there is just one variable species, or up to three or four separate entities present in New Zealand. The long-standing concept of two species is maintained here until further work can clarify the taxonomy of this difficult group.
Both species are endemic, diploid and sexually-reproducing, with I. alpina believed to be confined to the South Island, and I. kirkii to the North Island. However, the possibility of tetraploid, apomictic populations in both islands, and a possibly genetically-distinct population in Lake Ōmāpare, Northland (but now extinct in the wild), may complicate this simple geographic separation. I. alpina is a generally more robust plant than I. kirkii, best distinguished by its grey to white, smooth megaspores; it is widespread in montane and sub-alpine lakes and tarns throughout the South Island. I. kirkii is a more delicate plant, distinguished by its white, tuberculate megaspores; it is confined to a relatively small number of lakes and rivers in lowland areas of the North Island. It is now extinct in the Waikato Lakes and Wairua River, and is declining in its other localities.
Species of Isoetes are distinguished by their submerged or semi-aquatic habitat, tufts of linear, undivided leaves with conspicuous air chambers, and heterosporous spores produced in the swollen leaf bases.
Additional Information
| Field | Value |
|---|---|
| Data last updated | October 4, 2018 |
| Metadata last updated | August 31, 2018 |
| Created | August 31, 2018 |
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