Tetragonia is a genus of approximately 51 species of flowering plants in the family Aizoaceae, placed within the order Caryophyllales. The genus is distributed across temperate and subtropical regions of the Southern Hemisphere and parts of Asia, with its greatest diversity centered in southern Africa, where around forty species occur from Angola to South Africa. Additional species are found in Australia, eastern Africa, western South America (Peru and Chile), and across parts of Asia including Japan, Korea, Taiwan, southern China, Myanmar, and Vietnam.
Plants in the genus are herbs or small shrubs. Their leaves are alternate, succulent, and roughly kite-shaped. The flowers are typically small, yellow or greenish in colour, and may be solitary or clustered in the leaf axils; most are bisexual. The fruits are initially fleshy but become dry and woody at maturity — a distinctive feature reflected in the genus name, which derives from the Greek tetragonus, meaning "four-angled," in reference to the characteristic angular shape of the fruit.
The most widely known species is Tetragonia tetragonoides, commonly called New Zealand spinach, which has been cultivated globally as a warm-season leafy vegetable since its introduction to European horticulture in the late eighteenth century. Several other species are consumed locally: Tetragonia decumbens (Dune spinach) is a traditional food plant in its native southern Africa.
Etymology
The genus name Tetragonia derives from the Greek tetragonus, meaning "four-angled" (as in a tetragon), and refers to the distinctive angular shape of the plants' fruits.
Distribution
Tetragonia has its greatest diversity in southern Africa, with about forty species ranging from Angola to South Africa. The genus also occurs in Australia, eastern Africa (Kenya and Ethiopia), western South America (Peru and Chile), and across parts of eastern and southeastern Asia including Japan, Korea, Taiwan, southern China, Myanmar, and Vietnam.
Cultural Uses
The best-known member of the genus is Tetragonia tetragonoides, known as New Zealand spinach, which is widely cultivated as a summer leafy vegetable and was among the first southern hemisphere plants introduced to European cuisine. Tetragonia decumbens, called Dune spinach, is consumed locally as a traditional delicacy in its native southern Africa.
