Blackboard tree
Alstonia scholaris (L.) R.Br.
The blackboard tree (Alstonia scholaris), also called scholar tree or milkwood, is a large evergreen of the dogbane family (Apocynaceae) with whorled leaves, night-fragrant white flowers and paired pendulous follicles; the bitter bark yields medicines and the soft wood once made school blackboards — a famous shade tree of Hanoi streets.
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Blackboard treeBlackboard tree — Tree
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Blackboard tree — BarkBlackboard treeBlackboard tree — TreeOverview
The blackboard tree (Alstonia scholaris (L.) R.Br.), also called scholar tree, milkwood, white cheesewood or devil's tree, is a large evergreen of the dogbane family (Apocynaceae), 10–40 m tall, with a straight bole and buttresses when old. Leaves are whorled, 3–7 per node, oblong and leathery, glossy dark green above and paler beneath, with clear parallel side veins. The small cream-white, strongly fragrant flowers are borne in terminal umbellate cymes; in the tropics they peak in the rainy season and the scent carries strongly at night. The fruit consists of two slender pendulous follicles 15–40 cm long, packed with many tiny seeds each bearing a tuft of hairs for wind dispersal.
Updated by lebachungtdh@gmail.com · 10/10/2026
The greyish, rough bark is very bitter and rich in alkaloids (echitamine, alstonine, etc.). The soft, light, whitish wood was once used to make school blackboards (hence 'blackboard tree'), as well as pencils, crates and light panelling. Native to tropical Asia (India, Southeast Asia, China, Australia), it is widely planted as a street shade tree — famously along Trần Nhân Tông Street in Hanoi, Vietnam (the 'milk street'), and as 黑板树 in Taiwan. Bark, leaves and the white latex are used in folk medicine against malaria, dysentery, asthma and inflammations; modern research investigates the anticancer and antimicrobial activities of its alkaloids. Caution: the latex and parts of the plant can irritate the skin — not for self-medication.
Updated by lebachungtdh@gmail.com · 10/10/2026
Life cycle
From seed to productTree
Large evergreen tree with straight bole and broad crown.
Leaves
Whorled oblong leaves, glossy above.
Flowers
Small white night-fragrant flowers in terminal cymes.
Fruit
Two slender pendulous pods; hairy wind-borne seeds.
Distribution & origin
Share of recorded occurrences by region- Southeast Asia (incl. Vietnam)30%
- India & Sri Lanka20%
- East Asia (China, Taiwan)15%
- Australia & Melanesia15%
- Planted across the tropics (Africa, Americas)20%
Chemical composition
Relative content in agarwood resin- Water55%
- Fibre & cellulose (wood, bark)25%
- Alkaloids (echitamine, alstonine)5%
- Tannins5%
- White latex5%
- Essential oils & aromatics5%
Uses
- Urban landscape: street shade tree, famously lining Trần Nhân Tông Street in Hanoi — the 'milk street'; rainy-season blooms scent the night air
- Wood: soft and light — formerly made school blackboards, pencils, crates and light boards; rarely used today as it is brittle
- Folk medicine: bark, leaves and latex against malaria, dysentery, asthma and inflammations; alkaloids studied for anticancer and antimicrobial activity
- Ecology: flowers feed pollinators, seeds spread by wind; low pest burden and easy to grow — suited to green streetscapes
Properties
- Form
- Large evergreen tree
- Product
- Blackboard/wood products; folk medicines
- Hallmark
- Whorled leaves; night-fragrant flowers; long paired pendulous pods
- Uses
- Shade tree, timber, medicine
Habitat & conservation
The blackboard tree is sun-loving and tolerates dry or poorly drained sites; it grows naturally in secondary forest, riparian and moist valley habitats of tropical Asia, and is now common along streets, in parks and schoolyards. In Vietnam it is frequent in Hanoi, Huế and Ho Chi Minh City; the milk trees of Trần Nhân Tông Street are a familiar summer sight.
Conservation
A widespread, adaptable species not under threat — classified as Least Concern (LC). Dogbane family (Apocynaceae), genus Alstonia — the same family as oleander and Gymnema.
References
- 1Plants of the World Online — Alstonia scholaris (L.) R.Br. — Kew Science, 2026
- 2Alstonia scholaris (blackboard tree, scholar tree, devil's tree) — description, distribution, uses — Wikipedia tiếng Anh, 2026
- 3Cây sữa (Alstonia scholaris) — cây bóng mát & thuốc dân gian — Vietnamese Wikipedia & urban greenery references, 2026
- 4黑板树 / 糖胶树 Alstonia scholaris — 形態、分布與用途 — Wikipedia tiếng Trung, 2026
- 5Nguồn ảnh: Forestowlet (CC0); Steve Fitzgerald (CC BY-SA 4.0) — Wikimedia Commons,
- 6Nguồn ảnh: Ltn12345 (CC BY-SA 4.0) — Wikimedia Commons,