Tetragonia tetragonioides is a leafy groundcover also known as New Zealand spinach, Warrigal greens, kokihi, sea spinach, Botany Bay spinach, tetragon and Cook's cabbage. It is native to New Zealand, Australia, Japan, Chile and Argentina.
The species, rarely used by Maori or other indigenous people as a leaf vegetable, was first mentioned by Captain Cook. It was immediately picked, cooked, and pickled to help fight scurvy, and taken with the crew of the Endeavour. It spread when the explorer and botanist Joseph Banks took seeds back to Kew Gardens during the latter half of the 18th century. For two centuries, T. tetragonioides was the only cultivated vegetable to have originated from Australia and New Zealand.
The species prefers a moist environment for growth. The plant has a trailing habit, and will form a thick carpet on the ground or climb though other vegetation and hang downwards. The leaves of the plant are 3–15 cm long, triangular in shape, and bright green. The leaves are thick, and covered with tiny papillae that look like waterdrops on the top and bottom of the leaves. The flowers of the plant are yellow, and the fruit is a small, hard pod covered with small horns. The plant is a halophyte and grows well in saline ground.
It is grown for the edible leaves, and can be used as food or an ornamental plant for ground cover. As some of its names signify, it has similar flavour and texture properties to spinach, and is cooked like spinach. Like spinach, it contains oxalates; its medium to low levels of oxalates need to be removed by blanching the leaves in hot water for one minute, then rinsing in cold water before cooking. It can be found as an invasive plant in North and South America, and has been cultivated along the East Asian rim. It thrives in hot weather, and is considered an heirloom vegetable. The thick, irregularly-shaped seeds should be planted just after the last spring frost. Before planting, the seeds should be soaked for 12 hours in cold water, or 3 hours in warm water. Seeds should be planted 5–10 mm deep, and spaced 15–30 cm apart. The seedlings will emerge in 10–20 days, and it will continue to produce greens through the summer.
New Zealand spinach contains oxalates, which can cause kidney stones in some individuals. You can reduce the oxalates by boiling the leaves for two to three minutes before using them in a dish. After boiling, place the leaves in cold water to stop the cooking process. Use New Zealand spinach in salads, pastas, soups, omelets and any other dish you enjoy with leafy greens. One serving of New Zealand spinach equals 1 cup of chopped, fresh leaves. Consult your physician if you have a history of kidney stones to ensure New Zealand spinach is safe for you to consume.
One serving of New Zealand spinach contains just 8 calories, 0.8 grams of protein, 0.1 grams of fat, 1.4 grams of carbohydrates and 0.8 grams of dietary fiber. This low nutritional profile allows you to add it to meals without working against your daily goals. For example, you can stir 4 cups of New Zealand spinach into a salad, greatly increasing the serving size, while only adding 32 calories total.
New Zealand spinach is as excellent source of vitamin A, with 2,464 international units, or IU, per serving. Other notable vitamins and minerals in one serving of New Zealand spinach include 16.8 IU of vitamin C, 32 milligrams of calcium, 22 milligrams of magnesium and 16 milligrams of phosphorous.
The leaves of New Zealand spinach contain antioxidants, such as carotenoids, that reduce the amount of damage oxalates and free radicals do to your body. Consuming antioxidants reduces your risk of cancer, heart disease, Alzheimer’s disease, macular degeneration and several other conditions.
While New Zealand spinach contains very little protein, carbohydrates and dietary fiber, it is generally beneficial to include in your regular diet. The significant levels of vitamins, minerals and antioxidants provide your body with a boost that can increase your overall well-being and longevity. If you do not have access to New Zealand spinach regularly, substitute with regular spinach. It provides similar health benefits, and you can use it in any recipe that calls for New Zealand spinach.
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