Eurycoma longifolia (Simaroubaceae) is a small tree to 15 m high. Plants dioecious (flowers on a plant are either male or female). Leaves compound, long, and crowded at the tips of the branches. When the leaves fall they leave large scars on the stems. Leaflets are ovate-lanceolate, sessile or nearly so, and opposite. Flowers are borne in axillary panicles, mostly large and lax, and puberulous with short hairs. Flowers unisexual; the male always with a sterile pistil, female always with sterile stamens. Fruits ellipsoid or ovoid, 10-20 x 5-12 mm, green to blackish-red when ripe.

Ecology E. longifolia prefers acid and sandy soils at low altitude up to 700 m above sea level. Plants usually grow in beach forests, primary and secondary forests, mixed dipterocarp forests and also in heath forests.

In Riau Province, Sumatra, 1991, the author found that plants were growing in areas with an average temperature of 25C and 86% humidity. The soils in this area were found to be poor in nutrients, but mycorrhizal fungi were found growing near the plants and may indicate an association. Seedlings require shade, during which time they develop an extensive root system. Following juvenile stages, plants need stronger light to develop vegetative and reproductive parts. E. longifolia flowers and fruits throughout the year, with peak flowering from June-July and peak fruiting in September.

Distribution E. longifolia originates from South East Asia, including Indonesia, Malay Peninsula, Thailand, Laos, Cambodia and Vietnam. In Indonesia, this species only occurs naturally in Sumatra and Kalimantan.

Uses In South East Asia all parts of E. longifolia plants, in particular the roots, have long been used medicinally. The bark of the roots are used in the Malay Peninsula to cure fever, ulcers in the mouth, and intestinal worms. It is also used as a tonic after childbirth. People in some regions of Sumatra and Kalimantan also use the root as an anti-pyretic. In Lampung and Belitung it is used as a medicine for dysentery.

In Sabah and Kalimantan, a decoction of the bark is drunk to relieve pain in the bones, and a decoction of the leaves is used for washing itches. In Vietnam, people use the flowers and fruits as a medicine for treating dysentery. The Malays also use the paste of the plant to relieve headache, stomachache, pain caused by syphilis, and many other general pains. In Riau, where the author carried out research, people living in the surrounding forests drink a decoction of the root or stem to cure malaria. Currently, E. longifolia is mostly known as an aphrodisiac.

One of the most unique uses for E. longifolia is that of the Sakai ethnic group in Sumatra who use the plant as an amulet to protect people from the smallpox virus.

In areas where this species is used medicinally, such as Jambi and Riau in Sumatra, there is also often much superstition in relation to the harvesting of the plant or its parts. Harvesting must be conducted quietly and respectfully, as not to do so will result in the loss of the plant's benefits. The highest benefits will be obtained if the harvesters back is turned while pulling out the plant.

Phytochemistry The active constituents in E. longifolia, and many other species in the Family Simaroubaceae, include quassin, neo-quassin, glaukarubin, sedrin, eurycomanol which are mostly derivatives from compounds with 20 carbon atoms.

The Jamu Industry and future requirements In Indonesia in recent years there has been a sharp increase in demand for traditional medicines, 'jamu', resulting in an increase in the number and size of companies producing jamu. E. longifolia is used by both large and home industries in the preparation of jamu. As is the case with many other species used in the jamu industry, the collection of roots and other plant-parts is directly from wild plants. As a result, the harvesting pressure on wild populations is high and increasing with little effort yet to establish plantations. This and other major species used in the production of jamu need to be protected in remaining wild populations. In order for this to be feasible, plantations need to be established specifically for providing material to jamu manufacturers. Jamu manufacturers need to be responsible for the establishment of such plantations in the interests of maintaining and expanding their own industry.