# Tetragonia tetragonoides

**Aizoaceae**

**New Zealand Spinach**

*Tetragonia tetragonoides* is an annual herb that grows to heights of up
to 0.5 m. Plants have numerous stems that spread to heights greater than
3 dm. Leaves are 2-5 cm, with triangular and ovate blades.
Inflorescences include 1-3 flowers, which are 5 mm across with 4-5
spreading sepals. This species is native to the southern hemisphere; it
is a widespread littoral and estuarine species of the Pacific region
from South America to Japan and southeast China (including Norfolk and
Lord Howe Islands), New Zealand, the Kermadec Islands, New Caledonia,
Hawaii, and other Pacific Islands. Prescott (1984) considered this
species to be native to New Zealand and Australia. In South America, *T.
tetragonoides* is found naturally on both the southeastern and
southwestern coasts from central Chile and Uruguay southward to about 45
degrees south (Taylor 1994), and is widely naturalized in temperate and
subtropical parts of the world as an escape from cultivation. It is
common in California on sand dunes, bluffs, and the margins of coastal
wetlands below 100m.

Although typically littoral and estuarine throughout most of its natural
range, *T. tetragonoides* is also found in salty soils in some
subcoastal and inland areas in Australia, where it is commonly found
after rains in burned, cleared, or drought affected parts of northern
New South Wales and southern and central Queensland (Everist 1981).
Herbarium specimens in Australia have been used to confirm that T.
tetragonoides is a serious weed in wheat crops in Queensland, causing
wheat to be stunted, presumably due to competition for water (Gray
1997). The fruits of *T. tetragonoides* are dispersed by water and can
remain viable for more than a month in salt water (Taylor 1994).

*T. tetragonoides* was one of the first Australian plants used as food
by Europeans from Captain Cook and Sir Joseph Banks onwards, being
boiled and eaten like spinach, and some inland populations of this
species in Australia may be due to introductions from the coast for use
as a vegetable. Cook also used the plant as an antiscorbutic both in New
Zealand and Australia (Grey 1997). Low (1989) suggests that *T.
tetragonoides* became the first Australian food plant to be cultivated
overseas, the seeds being taken to Kew Gardens by Banks in 1771. Seeds
were later distributed from Kew to Europe and North America. Cooper and
Gambie (1991) report that this species contains certain alkaloids,
saponins, and tetragonin, a yeast growth regulator. It also exhibits
carbonic anhydrase activity, which apparently has opposing effects to
sulphonomide drugs. More recently, this species has been shown to
contain cerbrosides, compounds which have ant-ulcerogenic properties. It
has been used in traditional medicine in eastern Asia for the treatment
of esophageal and stomach cancer (Grey 1997).

High levels of soluble oxalate have been reported for *T. tetragonoides*
in Australia, and this species has also been reported to contain
alkaloids and significant amounts of saponin (Hurst 1942) and nitrates
(McBarron 1977). Levels of oxalates and nitrates are especially high in
young succulent plants, and concentrations of oxalates may reach levels
toxic to livestock (Everist 1981, McBarron 1977). However, as Everist
(1981) points out, livestock rarely eat these plants when they are young
and succulent, leaving it until stems are dry and presumable low in
oxalates.

**References**

Cooper, R.C., and R.C. Cambie. New Zealands Economic Native Plants.
Oxford University Press. Aukland.

Everist, S.L. 1981. Poisonous plants of Australia, ed. 2. Angus and
Robertson. Sydney.

Gray, M. 1997. A new species of *Tetragonia* (Aizoaceae) from arid
Australia. Telopea 7:119-127.

Hurst, E. 1943. The Poison Plants of new South Wales. Poison Plants
Committee of New South Wales, Sydney.

Low, T. 1989. Anyone for \"spinage.\" Austral. Nat. Hist.23: 108-109.

McBarron, E.J. 1977. Medical and Veterinary Aspects of Plant Poisons in
New South Wales. Dept. Agriculture NSW, Sydney.

Prakash, N. 1967. Life history of *Tetragonia tetragonoides* (Pall.) O.
Kuntz. Austral. J. Bot. 15: 413-424.

Prescott, A. 1984. *Tetragonia* (Aizoaceae) in: A.S. George (ed.) Flora
of Australia vol. 4 (AGPS: Canberra).

Taylor, C.M. 1994. Revision of *Tetragonia* (Aizoaceae) in South
America. Syst. Bot. 19: 575-589.