Of the 893 plant taxa (including hybrids) native to Stewart Island or Rakiura (Māori), the third largest Island in New Zealand located south of the South Island, 585 plants are native, and only a fraction are endemic (found nowhere else).

Much of this endemism is found in alpine areas, and is represented mostly by small daisies and buttercups. Brachyglottis stewartiae is the only endemic tree. The smaller offshore islands including: Tītī Islands, Codfish Island and islets in the Foveaux Strait are included as Stewart Island in this list. Although David Lyall collected the first plant from Stewart Island in around 1847–51, the first large survey of the flora of Stewart Island was published by botanist Leonard Cockayne in 1909. The most recent full treatment of the island's flora was written by Hugh Wilson in 1987. As Cockayne notes, Stewart Island is a largely unchanged landscape and as a result of this and its unique ecology, it has a national park which covers 85% of its area.

Although the vast majority of plants found on Stewart Island are found in other parts of New Zealand, several of the most common native mainland plants are not found there. Notably missing are any beech trees (Nothofagus sp.), which may be a result of glaciation, as well as kōwhai, māhoe, and kānuka, among others. When glaciers retreated from montane areas of Stewart Island 14,000 years ago, beech trees, as a result of their slow rate of spread, were not fast enough to recolonise. Other common plants were later introduced after their seeds were blown across the Foveaux Strait. Notable ecosystems in Stewart Island include: large dunes formed by pīngao, podocarp forests dominated by kāmahi and rimu, and coastal scrub of tree daisies. The ecosystems most significant to the endemic flora are the alpine and montane herbfields and grasslands–especially the "boggy meadow". The montane zone begins at around and is uniquely affected by very high winds and rates of rainfall, and a lack of sunshine. Although now protected, the endemic flora is put at risk by introduced mammalian predators such as possums and deer. As a result many species are threatened and listed as Naturally Uncommon or, in one plant's case, as Nationally Critical by the New Zealand Threat Classification System (NZTCS).

Vascular plants

Non-vascular plants

Notes

References

Bibliography

Further reading