Tetragonia tetragonoides

Common name: New Zealand spinach

Other common names: Warrigal greens, Warrigal cabbage, Warrigal spinach

Names in non-English languages: Spanish China

Description

New Zealand spinach or Warrigal Greens is a spinach plant originating in Australasia, its natural range extending from the North Island of New Zealand and from southern Australia, north along the east coast of the continent to the subtropics, as far north as the town of Rockhampton.

It is a short-lived perennial up to 50 cm (1.6 ft) tall, with a low-lying, sprawling, creeping habit of soft stems radiating outward up to 2 meters (6.6 ft) from the centre.

The leaves are arrowhead-shaped, 7 to 10 cm (2.8 to 4 in) long, soft, succulent and medium green. Fine hairs on the surface and on the stems give the plant a fuzzy, glistening appearance.

The flowers are small, yellow and arise from the leaf bases throughout the year. They are bisexual, with both male and female parts but require bees or other insects for pollination. The pollinated flowers are followed by angular, bell-shaped fruit up to 1.25 cm (0.5 in) long, with pointed horns, becoming dark brown when mature and with three or more small seed inside.

Use

The young leaves and stems were an important vegetable in the diet of the native peoples of Australian and New Zealand, long before Europeans arrived. Though still eaten today, its use is overshadowed by non-native species such as English spinach. However, it is still cultivated on a limited scale in home gardens and it is sometimes available as a niche vegetable at farmer's markets.

Unlike English spinach, it is suited to be grown in warm climates, tolerating high temperatures and is slow-bolting (reduced tendency to flower). This has encouraged its introduction and cultivation as a spinach crop in upland areas in the Philippines, as well as countries in Central and South America. 

Though not related to English spinach, the young leaves have a similar texture and flavour, albeit somewhat milder and slightly bitter. However, like English spinach, it is high in oxalic acid and only the young leaves and the stem tips should be eaten and these need to be blanched for a couple of minutes or longer and the water discarded as a precaution. After blanching it can be stored frozen like spinach or used straightaway in vegetable dishes, salads, pestos, quiches and stuffings.

It grows naturally in seashore environments and is used extensively in coastal dune plantings in its native range to control erosion and sand drift. 

Health use

The cooked leaves and stems are reportedly a good source of iron, calcium and phosphorus.

Climate

Grows naturally in sub-humid to moderately humid subtropical and tropical mid- to high-elevation climates, generally in areas with annual lows of 11 to 19 °C, annual highs of 22 to 29 °C, annual rainfall of 700 to 1800 mm and a dry season of 7 months or less.

Growing

New plants are usually started from seed, which benefit from pre-soaking in water for twenty-four hours before sowing. Performs best in rich or well-manured, free-draining loam and sand soils of a moderately acid to slightly alkaline nature, generally with a pH of 5.8 to 8.0, and sites with full to partial sun exposure.

The seed are best sown in spring to early summer in subtropical areas and toward the end of the rainy season in tropical areas, leading into the drier, cooler months and when there is sufficient soil moisture for good germination and growth.

Problem features

It has a creeping habit and seeds freely, producing viable seed that are easily dispersed by water. It is recorded as an invasive species, a term only applied to serious weeds, and is assessed as a high weed risk species for Hawaii, by the Hawaii Pacific Weed Risk Assessment project (HPWRA).

The uncooked leaves and stems have a high oxalic acid content which may adversely affect kidney function in some people.

Where it grows

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