Tamarind (Tamarindus indica, L. 1753)

Identity

Tamarind (Tamarindus indica L., 1753) is the sole species of the monotypic genus Tamarindus, a member of the Fabaceae family. It can crop for 50–60 years and live well beyond a century and a half, but cannot withstand freezing. Its epithet indica gives a misleading origin: the tree comes from tropical Africa, from Senegal’s Sudanian belt to East Africa, and reached India through an introduction several thousand years ago. ^{1 2}

The name tamarind derives from Arabic tamr hindi, literally “Indian date.” The expression describes the brown, sticky appearance of dried pulp rather than the tree’s true native range. Egyptians and Greeks already knew the fruit in the fourth century BCE, long before this name established the association with India. ^{2 3}

Recognition

Slow growth eventually produces a dense, rounded crown commonly 12–20 m (39–66 ft) tall and up to 30 m (98 ft) in exceptional specimens. Rough, fissured gray bark covers flexible branches that make the tree remarkably wind-resistant. ^{2 5}

Pinnate leaves have 10–20 pairs of small leaflets that fold each night, a movement called nyctinasty and shared with many legumes. Small flower clusters remain inconspicuous. The flowers are yellow with orange or red streaks, opening from pink buds. ²

Cinnamon-brown pods are flattened, irregularly curved and swollen, measuring 5–18 cm (2–7 in) long. A brittle shell encloses brown, sticky, strongly acidic pulp around hard, glossy seeds. Once the pod is opened, that pulp and the curved pod shape offer the most dependable confirmation of the species. ^{2 3}

Useful taxonomy

Several botanical synonyms from older descriptions now fall under the single accepted species Tamarindus indica:

• Tamarindus occidentalis Gaertn., an older name
• Tamarindus officinalis Hook., a historical synonym
• Tamarindus somalensis Mattei, a former species name
• Tamarindus umbrosa Salisb., another earlier name
• Tamarindus indica var. emarginata Chiov., a former variety name

Only one species belongs to the monotypic genus Tamarindus, making identification simpler than in larger genera. The accepted scientific name therefore provides a consistent reference without having to distinguish another species within the genus. ^{1 9}

Habitat and range

Wooded savannas in tropical Africa’s Sudanian belt, from Senegal to East Africa, form the native range. Tamarind grows on varied soils, from alluvial loam to porous limestone. It also tolerates salt spray and grows close to the coast. ^{1 2}

Several thousand years of cultivation in India led to the widespread belief that tamarind was indigenous to the subcontinent. It later spread throughout the tropical belt, including Southeast Asia, Pacific islands, the Caribbean, Mexico and Central America. Introduction to Hawaii dates to 1797. ^{2 5}

The IUCN assessment places tamarind in Least Concern. Its broad range and cultivation throughout the tropics protect it from a global extinction threat. ^{6 7}

Life cycle and reproduction

Seed remains viable for several months and germinates in roughly a week after sowing. With regular watering, a seedling reaches about 60 cm (24 in) in its first year and 120 cm (47 in) in its second. ²

Climate strongly affects the age at first fruiting: as early as 4 years in Madagascar, around 5 years in Mexico, but sometimes 10–14 years in India. Following summer flowering, pods take about 245 days from fruit set to ripen, gradually losing half their moisture. ²

A distinct dry season during ripening favors fruit production. Rainfall that is too frequent at that stage can prevent fruiting altogether. Mature trees then crop heavily for 50–60 years, before their productivity declines. ²

Even after that decline, a tree may live for nearly another century and a half. This exceptional lifespan places tamarind among the longest-lived fruit trees cultivated by people. ²

Uses and risks

Tangy tamarind pulp is a classic ingredient in Worcestershire sauce and many tropical cuisines, including sauces, chutneys, drinks and confectionery. Young leaves and flowers are also cooked as vegetables in parts of India and southern Africa. ^{2 3}

Hard, dense, purplish-brown heartwood is valued for furniture, tool handles and traditional mortars. Seeds supply an industrial gum used for textile sizing. ²

The ASPCA lists tamarind as non-toxic to cats, dogs and humans; its status in horses remains undetermined. ⁴

A widespread belief holds that few plants survive beneath a mature tamarind. This effect is attributed to the acidity of fallen leaves rather than actual toxicity of the species. In some African and Burmese traditions, the tree is considered sacred or inhabited by a protective spirit. ²

Varieties, look-alikes and related plants

Sweeter pulp is the main aim of horticultural selection. Makham Waan in Thailand and Manila Sweet, distributed by American agricultural services in Florida, are much sweeter than the wild type. Red-pulp populations are also considered superior in several producing regions, without constituting a distinct botanical variety. ²

Two groups of plants called tamarind do not belong to Tamarindus:

• Manila tamarind, Pithecellobium dulce, is an American legume with sweet pods rather than a close botanical match for true tamarind;
• Australian native tamarinds in the genus Diploglottis belong to an entirely different botanical family.

Use the accepted name Tamarindus indica to distinguish true tamarind. Neither of these common-name look-alikes shares its combination of 5–18 cm (2–7 in) pods, acidic pulp and membership of a one-species genus. ¹

Main sources

• Plants of the World Online / Kew, Tamarindus indica L.
• Purdue University NewCrop / Julia Morton, Tamarind (Tamarindus indica), Fruits of Warm Climates 1987
• Useful Tropical Plants Database (Ken Fern), Tamarindus indica
• ASPCA, Tamarindus indica toxicity entry
• USDA NRCS PLANTS Database, Tamarindus indica L. (TAIN2)
• IUCN Red List, Tamarindus indica assessment 2017
• INPN / MNHN, Tamarindus indica L.
• University of Florida IFAS, Tamarindus indica tree fact sheet
• International Plant Names Index, Tamarindus indica L.