''Entelea arborescens'' or whau is a species of malvaceous tree

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to New Zealand. ''E. arborescens'' is the only species in the genus ''Entelea''. A shrub or small tree to 6 m with large lime-like leaves giving a tropical appearance, whau grows in low forest along the coast of the

North Island The North Island ( , 'the fish of Māui', historically New Ulster) is one of the two main islands of New Zealand, islands of New Zealand, separated from the larger but less populous South Island by Cook Strait. With an area of , it is the List ...

and the northern tip of the

South Island The South Island ( , 'the waters of Pounamu, Greenstone') is the largest of the three major islands of New Zealand by surface area, the others being the smaller but more populous North Island and Stewart Island. It is bordered to the north by ...

. The dry fruit capsules are very distinctly brown and covered with spines. The common name ''whau'' is a

Māori Māori or Maori can refer to: Relating to the Māori people * Māori people of New Zealand, or members of that group * Māori language, the language of the Māori people of New Zealand * Māori culture * Cook Islanders, the Māori people of the Co ...

word that appears to derive from the common Polynesian word for

hibiscus ''Hibiscus'' is a genus of flowering plants in the Malva, mallow family, Malvaceae. The genus is quite large, comprising List of Hibiscus species, several hundred species that are Native plant, native to warm temperate, Subtropics, subtropical ...

, particularly '' Hibiscus tiliaceus'', which it superficially resembles. Alternate names include 'New Zealand mulberry', 'corkwood' and 'evergreen lime'.

Description

Within the

Malvaceae Malvaceae (), or the mallows, is a family of flowering plants estimated to contain 244 genera with 4225 known species. Well-known members of economic importance include Theobroma cacao, cacao, Cola (plant), cola, cotton, okra, Hibiscus sabdariffa, ...

, ''Entelea'' is placed within tribe Sparrmannieae and subfamily Grewioideae, a position confirmed by ndhF

DNA sequence A nucleic acid sequence is a succession of bases within the nucleotides forming alleles within a DNA (using GACT) or RNA (GACU) molecule. This succession is denoted by a series of a set of five different letters that indicate the order of the nu ...

data. As is the case with most malvaceous plants, ''E. arborescens'' has alternate, stipulate foliage. The bright green, obliquely cordate leaves are large (10 to 20 cm long), and have from 5 to 7

nerves A nerve is an enclosed, cable-like bundle of nerve fibers (called axons). Nerves have historically been considered the basic units of the peripheral nervous system. A nerve provides a common pathway for the electrochemical nerve impulses called ...

and long petioles. The flowers are borne profusely between early spring and mid-summer. They have 4 or 5 sepals and 4 or 5 petals. They are 2 cm in diameter, scented, white, with a central tuft of densely-packed yellow stamens. The brown seed capsules, which are 1½ cm long, bear 2½ cm long rigid bristles. Whau has very lightweight wood, rivalling

balsa ''Ochroma pyramidale'', commonly known as balsa, is a large, fast-growing tree native to the Americas. It is the sole member of the genus ''Ochroma'', and is classified in the subfamily Bombacoideae of the mallow family Malvaceae. The tree is fa ...

(''Ochroma pyramidale'') for lightness, and less dense than cork ( about half the density). The wood was used by

to make ''pōito'' (fishing floats), ''kārewa'' (buoys) and ''mōkihi'' (rafts). The pale brown wood forms several bands of unlignified

pith Pith, or medulla, is a tissue in the stems of vascular plants. Pith is composed of soft, spongy parenchyma cells, which in some cases can store starch. In eudicotyledons, pith is located in the center of the stem. In monocotyledons, it ex ...

-like

parenchyma upright=1.6, Lung parenchyma showing damage due to large subpleural bullae. Parenchyma () is the bulk of functional substance in an animal organ such as the brain or lungs, or a structure such as a tumour. In zoology, it is the tissue that ...

per year. This is a characteristic shared with related plants including '' Sparrmannia'', and causes there to be no distinct growth rings in the wood. File:Entelea arborescens (Whau) trunks with epicormic shoots.jpg, Whau trunks with epicormic shoots File:Entelea arborescens Auckland Botanic Gardens 2.JPG, Seed pods File:Whautree02.jpg, Foliage and flowers

Distribution

The species is extremely light-demanding and is unable to live under an unbroken canopy. It cannot tolerate even moderate cold, or a very dry or ill-drained soil. Its occurrence is sporadic even in undisturbed coastal forest. In lowland rain-forest whau is rare, found only beside streams in valleys near the coast where open ground and sufficient warmth and light are found. Although whau occurs here and there in Nelson and Marlborough in the

, occurrence is local south of Lat. 38°. The plant has never been found more than 8 km. from the sea (Waitākere Stream, near Auckland), nor higher than 350 m. Extreme minimum temperatures for localities where Entelea really thrives are always, so far as the records show, well above 0 °C.

Ecology

In its natural habitat the tree depends mainly for success upon its prodigious seed production, the remarkably long life of the seed, and, after germination, rapid growth. In forest, whau is essentially a transient, opportunist species. The characteristics which cause it to be effective in such a role include: its ability to quickly occupy ground where light has been temporarily let into the forest; its tremendous rate of growth; its ability to rapidly produce fruit; its enormous seed production, especially as it is about to die; and the fact that its seeds are capable of germinating as soon as the capsules open. Whau seeds can be stimulated into growth by fire after lying on the surface of the ground for many years. Having germinated, whau establishes itself with striking rapidity. In a study on Taranga (Hen Island), in favourable conditions whau was often the first new plant to appear, followed by '' Urtica ferox'' (tree nettle), ''

Macropiper excelsum ''Piper excelsum'' (formerly known as ''Macropiper excelsum'') of the pepper family (Piperaceae) and commonly known as kawakawa, is a small tree of which the subspecies ''P. excelsum'' subsp. ''excelsum'' is endemic to New Zealand; the subspe ...

'' (kawakawa), '' Coprosma macrocarpa'' (coastal karamu) and '' Coprosma lucida'' (shiny karamu); forest-dominating trees were slower to come in – '' Corynocarpus'' (karaka) most quickly, followed by ''

Beilschmiedia tawa ''Beilschmiedia tawa'', commonly known as the tawa, is a New Zealand broadleaf tree common in the central parts of the country. Tawa is often the dominant canopy tree species in lowland forests in the North Island and the north east of the Sou ...

'' (tawa).

Cultivation

Preferring a rich moist

loam Loam (in geology and soil science) is soil composed mostly of sand (particle size > ), silt (particle size > ), and a smaller amount of clay (particle size < ). By weight, its mineral composition is about 40–40–20% concentration of sand–si ...

, whau can be grown outdoors in sun or light shade in mild climates, or in a conservatory or glasshouse in cold climates. It is intolerant of drought and is able to withstand barely 3 °C of frost. Propagation is from seed, which is available commercially. It also strikes readily from hardwood cuttings about 20–30 cm long with leaves and twigs removed. Thrust deep into gritty damp soil in black planting bags and covered with a wet sack or newspaper for a week to keep moist; new leaves will appear after about three weeks. Best left a few months until strong re-growth is obvious before transplanting.

References

* L. H. Millener
'A Study of Entelea arborescens R. Br. (Whau): Part I. Ecology'
''Transactions and Proceedings of the Royal Society of New Zealand'', Volume 76, 1946–47, pp. 267–288. {{Taxonbar, from1=Q15813022, from2=Q3315478 Grewioideae Monotypic Malvales genera Trees of New Zealand Endemic flora of New Zealand