What is Alstonia?

Alstonia is a genus of evergreen trees and shrubs in the dogbane family, Apocynaceae. There are Alstonia species native to tropical areas of Africa, Australia, Central America, Polynesia, and southeast Asia. The trees can reach 200 feet (60 meters) in height. There are five sections within the Alstonia genus: Alstonia, Blaberopus, Dissuraspermum, Monuraspermum, and Tonduzia. The bark, leaves, and sap have many uses in traditional medicine.

These plants feature small, fragrant flowers that may be white, pink, yellow, or green. They mature into dark blue, pod shaped fruits. A. macrophylla, commonly called devil tree, is also called wig banyan in Sri Lanka because the flowers are thought to resemble a woman's long wig.

A. longifolia, the only species growing in Central America, is usually a shrub, but can reach heights of 66 feet (30 meters). A. constricta, commonly called quinine bush or bitterbark, grows only in Eastern Australia and is the only subtropical member of the genus. Its bark is used in homeopathic and traditional medicine to treat dysentery and diarrhea, fever, and parasitic worms. A. angustifolia, native to Indonesia, Malaysia, the Philippines, and Vietnam, is used to treat headache. The sap of various Alstonia species is sometimes used to treat cough, fever, and sore throat, though it is poisonous.

A. scholaris, native to South and Southeast Asia, China, and Australia, is another important medicinal species. Commonly called blackboard tree, Indian devil tree, and pulai, A. scholaris is used to treat malaria, as an alternative to quinine. The bark has also historically been used to treat diarrhea and fever, to promote blood flow, and to heal wounds, while the leaves have been used to treat beriberi.

The wood of A. scholaris is used in coffins in Sri Lanka and for net floats and utensils in Borneo. Other species are used as commercial timber in Indonesia and Malaysia. Timber from plants of the Alstonia section are light, while those of the Dissuraspermum and Monuraspermum sections are heavier.

Some Alstonia species are very rare. A. annamensis grows only in Vietnam and is endangered. A. beatricis is of vulnerable conservation status and grows only in Indonesia. Other vulnerable species are A. breviloba, limited to Papua New Guinea, A. henryi, which grows only in China, and A. penangiana, endemic to Malaysia. A. marquisensis is endemic to French Polynesia, and A. rupestris is endemic to Thailand, but neither of these is a threatened species.

Alstonia is a genus of flowering plants in the dogbane family, Apocynaceae, comprising about 60 species. These trees are native to tropical and subtropical regions of Africa, Madagascar, Asia, and the Western Pacific. They thrive in a variety of habitats, from rainforests to savannas, and are particularly common in secondary forests where they can grow rapidly in clearings.

Alstonia trees are known for their distinctive whorled leaves, which are arranged in a tiered fashion around the stem, and their milky sap. They can grow quite tall, with some species reaching up to 45 meters in height. The bark is often used in traditional medicine, and the wood is valued for its lightness and workability.

Yes, Alstonia has a long history of medicinal use, particularly in traditional Asian and African medicine systems. The bark of several species, such as Alstonia scholaris, is believed to have antimalarial, analgesic, and antipyretic properties. According to ethnopharmacological research, extracts from Alstonia have been used to treat a variety of ailments, including fevers, respiratory issues, and digestive problems.

Alstonia trees play a significant role in their ecosystems by providing habitat and food for wildlife. Their flowers are a source of nectar for pollinators like bees and butterflies, while the dense foliage offers shelter for birds and insects. Additionally, as fast-growing trees, they help in reforestation efforts and carbon sequestration, contributing to the fight against climate change.

Alstonia wood is indeed used commercially; it is prized for being lightweight and easy to work with. It's commonly used for making matchsticks, packing cases, pencils, and even as a core material in plywood. The wood of some species, like Alstonia constricta, is also used in paper manufacturing due to its suitable fiber properties.

Some Alstonia species are facing threats due to habitat loss and overexploitation. Deforestation for agriculture and urban development has reduced their natural habitat, while the medicinal and commercial value of their bark and wood has led to overharvesting. Conservation efforts are necessary to ensure the survival of these species, particularly those classified as vulnerable or endangered.