Alectryon excelsus

Tītoki
A mature tītoki tree near Tangoio
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Rosids
Order:	Sapindales
Family:	Sapindaceae
Genus:	Alectryon
Species:	A. excelsus
Binomial name
Alectryon excelsus Gaertn.

Alectryon excelsus, commonly known as tītoki,^[1] or sometimes New Zealand oak, is a shiny-leaved tree native to New Zealand. It is in the family Sapindaceae. It lives in coastal and lowland forests throughout most of the North Island and from Banks Peninsula to central Westland in the South Island.

Alectryon excelsus is a sub-canopy tree growing to 9 metres (30 feet) in height. It has a twisting trunk with smooth dark bark, spreading branches and pinnate leaves.^[2] Adult leaflets do not have marginal teeth or usually have very few, blunt and shallow marginal teeth and usually leaflet margins are downturned, whereas, in juvenile leaflets have leaflets with strong teeth and flat along the edges.^[3] The length of this tree leaf are around 10–30 cm.^[4] This tree has pale grey to almost black skin with a smooth skin texture and has a stem diameter that reaches 50 cm or more.^[3]

Alectryon excelsus produces small purple flowers in spring and the seeds take up to a year to mature. The female flower has a small anther ('without pollen') and a short stemmed sari, whereas, the male flower has a long dangling stamen around the vestigial ovary.^[3] The colourful seed is initially contained in a hairy woody capsule which splits revealing bright red and black unpalatable fruit (the black portion being the seed).

The species was first described by Joseph Gaertner in 1788 in the work De Fructibus et Seminibus Plantarum, using the name Alectryon excelsum. Gaertner named the species the type species of the genus Alectryon.^[5][6]

There are two subspecies of Alectryon excelsus: Alectryon excelsus subsp. excelsus, the variety found widely across New Zealand, and Alectryon excelsus subsp. grandis, found exclusively on the Three Kings Islands.^[7] This subspecies was first described in 1892 by Thomas Cheeseman, who raised the subspecies to species level in 1891, calling it Alectryon grandis. The taxon's status as a subspecies was restored in 1999.^[8]

The Māori language name tītoki originates from the Polynesian word taputoki, which refers to trees in Sapindaceae (the soapberry family) in Tongan and Samoan, and the laurel family in Niuean. The element toki refers to the Polynesian word for adzes.^[7][9] The species epithet excelsus means tall or grand, and names used by European settlers included New Zealand ash and New Zealand oak.^[7]

Alectryon excelsus is native to New Zealand but can be found in other places around the world. The tree has been located along street verges in San Francisco.^[10] It is the only member of the Alectryon genus found in New Zealand.^[7]

A. excelsus can be found from the North Island to the Westland area of the South Island.^[3] The farthest west would be to about Bruce Bay. It is commonly seen in lowland forests from sea level to 600 metres as well as in coastal forests of the North Island. This tree has been seen all over the South Island.

A. excelsus is likely to grow anywhere from lowland forest areas and exposed coastal area sites along with sandy plains.^[3] In sandy plains, Alectryon excelsus is often paired with Beilschmiedia tawa (tawa).

This tree likes to grow in the places that have a lot of water such as wetlands.^[4] Tītoki tree gravitates towards moist soil which contains many nutrients for growth along with fertile alluvial and sandy soils.^[3] The location characteristics best suited for this tree are: ‘fertile, well-drained soils along riverbanks and associated terraces'.^[11] The plant can grow in conditions from semi-shade to full sun.^[10]

The ovary develops into a hairy and dense capsule with rusty, brown hair. In about one year, the capsule will mature and divide the red flesh tissue that surrounds one large seed.^[3] From this cleavage, it will show one large seed which is hidden for one year in the capsule and then, the seeds will fall to the ground and will grow into trees if they fall in the right place to support the growth of the tree or the seeds will be spread by New Zealand birds such as the tūī, kererū, kōkako and black birds.^[12] This tree will flower from spring to early summer.^[3] Some flowers of this tree are bisexual because female flowers and male flowers are not borne on the same tree.^[3]

The fruit of this tree is usually eaten by possums and birds.^[3] Some insects enjoy chewing the bark and the leaves.^[12] In addition, the leaves on a small tītoki tree will be targeted by deer.^[12] The parasite known as the tītoki fruit borer destroys the seeds of this tree by living inside the capsule and eating the seeds.^[12]

The tītoki tree is one of the native trees in New Zealand that was traditionally planted by Māori. Usually, the pulp fruit from this tree is consumed by Māori while the wood is commonly used for making trainers and wheels because the wood is very elastic and strong.^[12] While the berries are edible, they were not a major part of traditional diets, tending to be sour and dry, and tītoki berries tended to be a famine food.^[7]

Tītoki seeds were used to create hinu tītoki, an oil that was a traditional status symbol. The oil was used as a hair oil, incorporated into body paint, believed to ward off sandflies, and was used as a perfumery base, and could be steeped in aromatic leaves from plants such as tarata.^[7] Tītoki oil also has uses in traditional rongoā medicine, by being applied to wounds, or being used in massage.^[7] Traditional production of oil involved crushing the tītoki seeds inside tourniquet-style flax bag or an elongated woven basket called ngehingehi (akin to a Brazilian tipiti) alongside heated stones, and collecting the greenish oil as the bag is squeezed.^{[12][1][9][13][7]}

Early European settlers used the oil for a range of uses including for machinery, however this fell out of fashion when the whaling industry in New Zealand expanded, and made whale oil cheaper to procure.^[7] Tītoki wood was used by early settlers to create items such as coaches and cabinets.^[7]

In the 1980s, the Department of Scientific and Industrial Research developed a liqueur made from tītoki berries, promoting its use in desserts and cocktails.^[14] The fruit attributes sweet and astringent taste factors to the alcohol. This product has been distilled and exported to Australia, Fiji, Japan, and the United Kingdom.^[15]

Tītoki trees are a common sight in suburban New Zealand, as they are commonly used in street planting.^[7]

• 
  Ripe fruits, the capsule splits open, revealing a black seed and flashy red aril
• 
  Herbarium specimen of leaves and bark
• 
  Tītoki foliage
• 
  Alectryon excelsus subsp. grandis leaves
• 
  Tītoki trees in street planting at Wynyard Quarter, Auckland

• Metcalf, Laurie, 2002. A Photographic Guide to Trees of New Zealand. Auckland: New Holland.
• Salmon, J.T., 1986. The Native Trees of New Zealand. Wellington: Heinemann Reed.

• New Zealand Plant Conservation Network: Alectryon excelsus excelsus. Accessed 4 October 2010
• New Zealand Plant Conservation Network: Alectryon excelsus grandis. Accessed 4 October 2010
• "Alectryon excelsus Gaertn". Atlas of Living Australia.
• Media related to Alectryon excelsus at Wikimedia Commons