There is an extreme range of growth size within the genus, from huge clump-forming species to diminutive mat-forming creepers.
The giant of the genus is the South American Gunnera manicata, giant rhubarb.
This impressive plant will form clumps exceeding 3m wide and reach heights of 2.5m.
In contrast to these mega-herbs, you will have to look hard to see our native species of which we have five, all endemic, and not one of them exceeding 15cm in height.
Gunnera dentata and G. prorepens occur on the North, South and Stewart Islands and G. monoica also occurs on the Chathams.
Found only in the South Island, G. densiflora has a distribution limited to the Inland Kaikoura Ranges and inland Canterbury from Lake Tennyson to Craigieburn Range.
My favourite of the native Gunnera species is G. hamiltonii, which is one of New Zealand's rarest plants, known only from a very small number of wild populations on the south coast of the South Island and Stewart Island.
This diminutive plant forms compact rosettes of bronzey-coloured foliage off short, creeping stolons (stems).
- Gunnera hamiltonii carries its male and female flowers on separate plants. It is thought that the Stewart Island populations are all male, which severely limits its reproductive capabilities.
- Our native species grow from sea level to subalpine regions in damp grassland or sand, often near water.
- All species require good moisture levels and some sun.
- G. hamiltonii can be seen in the native coastal plant border in the upper botanic garden.
- G. manicata can be seen on the slopes of the arboretum, above the lower botanic garden.
Shirley Stuart is curator of the native plant collection at the Dunedin Botanic Garden.
