Common name: Chaya

Chaya or Mayan spinach is a shrub or small tree native to Central American, its natural range extending from the Yucatan Peninsula in Mexico, south to Guatemala and Belize. It is cultivated nowadays in East Africa, Southeast Asia, The Philippines, Australia, South America and the Caribbean, mainly as a home-garden vegetable.

There are two known subspecies, one of which (subsp. chayamansa) is cultivated for its leaves, which are cooked as a vegetable. The other (subsp. aconitifolius) is the wild form. Although sometimes also cultivated, the leaves of the wild form are covered in hairs that are an irritant to the skin.

The two subspecies also have different flowering and seeding habits, with the cultivated form seldom, if at all, producing seed. In contrast, the wild form freely produces viable seed, which contributes to it being a weed. For this reason, only the cultivated form is described here.

It can grow into a small 6 m (20 ft) tall tree with a densely branched rounded crown. However, it is more typically a shrub under 3 m (10 ft) and comes in different varieties, which are mainly distinguishable by the size and shape of the leaves. The stems are soft-wooded and exude a milky sap when wounded.

The leaves are large, up to 30 cm (12 in) long, nearly as wide, deep green and come in various shapes, ranging from shallow to deeply lobed and from slightly to strongly toothed on the margins, dependant on the variety. Each leaf is held on a long leaf stalk that resembles the leaves and leaf stalks of Cassava (Manihot esculenta), a close relative. Some varieties have hairs that irritate the skin, but they are much smaller and fewer than on the leaves of the wild form and are mostly limited to the leaf stalk.

The flowers are small and insignificant, white, and either female or male together in clusters on long flower spikes. They bloom on-and-off throughout the year but are at their fullest in summer, which coincides with the rainy season in its native range. The fruit that follow are few in number, rarely mature to produce seed, and any seed produced are usually not viable.

Use

The leaves are harvested and cooked as a vegetable. However, they must be cooked first for at least a few minutes because they contain cyanogenic glycoside, a poison also common in cassava and uncooked bamboo shoots. Fortunately, this poison evaporates during the cooking process and is not retained in the cooking liquid or sauce.

Because the leaves need cooking for some time, they are not recommended for use in stir-fries as the cooking time may be too short, and they are best suited for use in stews, casseroles and soups. Unlike spinach, they shrink very little when cooked, have a firm cabbage-like texture and flavour, and are nutritious.

Plants in home gardens are sometimes kept as a hedge and trimmed to 2 m (7 ft) or shorter to make it easy to harvest the leaves. Chaya leaves can be harvested year-round as long as no more than half of the leaves are removed from the plant, allowing it to continue growing and being productive.

Health use

The leaves have a high protein, vitamin C and calcium content. They are also rich in phosphorus, iron, thiamin, riboflavin, and niacin. Their protein content reportedly approaches 6% of their dry weight, and their vitamin C and calcium content is about 165 mg and 199 mg, respectively, per 100 gram serving.

Climate

Grows naturally in sub-humid to humid subtropical and tropical lowland climates, generally frost-free areas with annual lows of 16 to 25°C, annual highs of 25 to 35°C, annual rainfall of 1000 to 2500 mm and a dry season of 2 to 7 months.

Growing

New plants are mostly started from cuttings, as seed are not readily available. Good results have come from using cuttings of one to two-year-old wood taken from selected varieties. Cuttings measuring 15 to 30 cm (6 to 12 in) are dried under shade for around a week before being planted. The wood, being soft, is susceptible to fungal attack under humid conditions and drying the cuttings before planting helps to overcome this problem. For this reason, the cuttings are never placed in water or wetted before planting.

Performs well on a wide range of soils, though is most productive on rich, free-draining loam and sand soils of a moderately acid to slightly alkaline nature, generally with a pH of 5.5 to 8.0 and on sites with full to partial sun exposure. Plants grown under partial sun exposure tend to produce leaves that are more tender than those under full sun. It is moderately tolerant of slow-draining or waterlogged soils.

The leaves are not usually attacked by leaf-eating insects, which is often a challenge when growing other spinach-like plants for their leaves.

Commonly cultivated varieties include 'Chayamansa' and 'Redonda'.

Problem features

The leaves contain cyanogenic glycoside, a cyanide type poison also common in cassava and uncooked bamboo shoots. Stinging hairs may be present on the leaves and leaf stalks of some varieties.

Books

• Francis, J. K. and Liogier, H. A. 1991, Naturalized exotic tree species in Puerto Rico, General technical report SO-82, USDA Forest Service, Southern Forest Experiment Station, New Orleans

• Gargiullo, M. B & Magnuson, B. L. & Kimball, Larry D. 2008, A field guide to plants of Costa Rica, Oxford University Press, Oxford

• National Research Council (Board on Science and Technology for International Development) 1975, Underexploited tropical plants with promising economic value, National Academic Press, Washington D. C.

• Randall, R. P. 2002, A global compendium of weeds, R.G. and F.J. Richardson Press, Melbourne

• Randall, R. P. 2007, The introduced flora of Australia and its weed status, Cooperative Research Centre for Australian Weed Management, Glen Osmond, South Australia

• Schubert, T. H. 1979, Trees for urban use in Puerto Rico and the Virgin Islands. U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station, New Orleans

• Sterling, D. 2014, Yucatán : recipes from a culinary expedition, First edition, Austin, TX University of Texas Press