Biology:Nikau

Nikau
Conservation status
Conservation Dependent (IUCN 2.3)
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Clade:	Commelinids
Order:	Arecales
Family:	Arecaceae
Genus:	Rhopalostylis
Species:	R. sapida
Binomial name
Rhopalostylis sapida H.Wendl. & Drude

The nikau (Māori: nīkau; Rhopalostylis sapida) is a palm tree endemic to New Zealand, and the only palm native to mainland New Zealand.

Etymology

Nīkau is a Māori word; in the closely related Eastern Polynesian languages of the tropical Pacific, it refers to the fronds or the midrib of the coconut palm.

Distribution

Nikau grove, Paraparaumu

The nikau palm is the only palm species endemic to mainland New Zealand. Its natural range is coastal and lowland forest on the North Island, and on the South Island as far south as Okarito mostly in humidity (43°20′S) in the west and Banks Peninsula (43°5′S) in the east. It also occurs on Chatham Island and Pitt Island/Rangiauria to the south-east of New Zealand, where it is the world's southernmost palm at 44° 18'S latitude.

The nikau grows up to 15 m tall, with a stout, green trunk which bears grey-green leaf scars. The trunk is topped by a smooth, bulging crownshaft up to 1m long. The fronds are up to 3 m long, and the closely set, sometimes overlapping leaflets are up to 1 m long. The inflorescence is multibranched and from 200 to 400 mm long. The tightly packed flowers are unisexual and coloured lilac to pink. Male flowers are borne in pairs, and have six stamens. The female flowers are solitary. The fruit is elliptic or oblong, and generally measures about 10 by 7 mm, and is red when ripe. The nikau produces flowers between November and April, and fruits ripen from February to November, taking almost a year to fully ripen. These are a preferred food of the kereru, the native wood pigeon.

Cultivation

Ripe fruit of the nikau

The nikau makes an excellent potted plant, and is quite hardy. It tends to be slow-growing. It grows readily from seed if the fruit is soaked in water for a few days and then gently scrubbed to remove the flesh. The seed will then germinate readily if placed in sealed plastic bags in partial shade, after which they can be planted in deep pots. The pots should be tall and narrow to provide room for the taproot and to lessen the likelihood of root damage when transplanting.

Transplanting juveniles is generally successful if the main root is left intact. The nikau does not have a true tap root. Once the main root has been established to a fairly shallow depth of about 400 mm, its roots take on form consistent with other palms. Successful transplanting is possible, but nikau is very fickle if any trunk is present. It is best done in summer, but a substantial root ball should be preserved, and shade should be provided at the new location - at the very least by tying the outer fronds closer to the centre. Ground watering is recommended because crown watering can induce terminal rot at the very slow-growing new spike. Delays should be avoided in getting the nikau into its new ground, and substantial die-back of all but the central spike can be expected.

The nikau thrives on cool temperatures, but is not subject to freezing weather in its natural habitat. It can survive a few degrees of frost, but it is damaged even more severely by sudden large drops in temperature even above freezing. It does well in areas with a mild Mediterranean climate.

Variation

The Chatham Islands nikau is particularly distinctive

Outstanding nikau palm

The nikau palm shows considerable variation in the wild. Plants from the South Island and the offshore islands of the North Island have larger, more-gracefully-arching fronds and are popular in cultivation. The Chatham Islands form is particularly different, having a distinct juvenile form and larger fruits, and a thicker covering of fine hairs on the fronds. More research is needed into its precise relationship with the mainland form. The New Zealand nikau palm is very similar to Rhopalostylis baueri of the Kermadecs and Norfolk Island, which can be distinguished by its more rounded or oval fruits, and by its leaflets which are broader than those found in most populations of R. sapida.

Uses

Māori found many uses for the nikau palm. The bases of the inner leaves and the young flower clusters were eaten raw or cooked. Food was wrapped in the leaves for cooking, and the old fibrous leaves were used for baskets, floor mats, and waterproof thatch for buildings.

References and external links

• "Rhopalostylis sapida". New Zealand Plant Conservation Network. http://www.nzpcn.org.nz/flora_details.asp?ID=1259. Retrieved 2010-10-02. 
• "Rhopalostylis sapida". Flora of New Zealand. http://floraseries.landcareresearch.co.nz/pages/Taxon.aspx?id=_9d8e5040-9e69-46b3-8fda-60f89534d9ff&fileName=Flora%202.xml. Retrieved 2007-07-10. 
• Dowl (1998). "Rhopalostylis sapida". IUCN Red List of Threatened Species 1998. https://www.iucnredlist.org/details/38686/0. Retrieved 11 May 2006. old-form url
• New Zealand native plant website: Rhopalostylis sapida
• Nikau images and artworks, Museum of New Zealand Te Papa Tongarewa

Wikidata ☰ Q1990136 entry