Kingdom: Plantae
(unranked): Angiosperms
(unranked): Monocots
Order: Asparagales
Family: Asteliaceae
Genus: Astelia
Species: Astelia chathamica
Synonyms: Astelia nervosa var. chathamica, Astelia cv. Silver Spear.
Common name: Chatham Islands Astelia, Silver Spear, Kakaha, Chatham Islands Astelia.

This plant is an astelia from the wet, peaty soils in the Chatham Islands. Astelia chathamica and is one of the largest and most distinctive species of the taller-growing Astelias. It forming large clumps up to 1.5m or so tall with broad stiff, erect flax-like silver leaves (up to 2m long by 10cm wide), drooping at the tips. The leaves are covered with a clear pellicle giving it a silvery sheen.
In mid to late spring the female plants produce an inflorescence of pale yellowish green flowers.  The flowers are mostly dioecious, although individual plants may produce some hermaphrodite flowers. These are small and starry in appearance, with six tepals. The flowers are followed by 1x1 cm orange berries fruit in February to June. The seeds are black and glossy. 
This plant is now sold in nurseries.

This plant was photographed at Otira Wilton Bush Reserve.
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This plant can be seen just east of Spencer Place entrance next to the seat.Astelia chathamica Silver Spear -3.JPG

Te Henui Walkway near Adams Point
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Berries just forming after flowering. 
Chatham Island Kakaha Astelia chathamica .JPG

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Plant with ripe orange/red berries March
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The upper surface of a leaf
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The underside of a leaf.
Chatham Islands Astelia Astelia chathamica-002.JPG

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/