Alstonia rupestris Kerr - APOCYNACEAE

Synonym : Blaberopus rupester (Kerr) Pichon

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Botanical descriptions Habitat and ecology Distribution

Botanical descriptions :

Diagnostic characters : Trees with whorled sessile leaves, 50-80 pairs of secondary veins, glands on the leaves axils.
Habit : Columnar tree up to 25 m tall, branches ascending to main trunk.
Trunk & bark : Bark greyish, deeply lenticellate, inner bark pale reddish.
Branches and branchlets or twigs : Branchlets glabrous and strongly lenticellate.
Exudates : Latex white, copious.
Leaves : Leaves small, grouped in whorls of 3 - 5, sized 3-13 by 0.5-2.5 cm, elliptic, apex acuminate, base attenuate and decurrent, margin entire, blade subcoriaceous and glabrous with glands on the axils.
Midrib raised above, primary vein single, secondary veins more than 50 pairs, oblique to the midrib, and closely parallel, tertiary veins ramified admedial.
Stipules absent.
Inflorescences or flowers : Flowers small, whitish or creamy, densely velvety, many in number, with sweet smell.
Fruits : Fruit compound of a pair of follicles, 6.1-7.5 cm long, 5 mm wide, glabrous.
Seeds : Seeds many, glabrous and ciliate.

Habitat and ecology :

On limestone in open forest from 500 m to 1800 m .
Flowering period: February to April; fruiting time: April to May.

Distribution :

China, Thailand (Type), Laos (Bolikhamxay).

Remark/notes/uses :
The wood is often used for coffins and as a plywood core. An infusion of the crushed leaves is used to clean infected wounds. The bitter bark and latex yield a tonic and anti-septic medicine.

Specimens studied :
BT 65 (Herbarium of Faculty of Sciences-NUoL, NHN-Leiden and CIRAD-Montpellier).

Literature :
Flore Générale de l’Indochine. 1930-1933. Vol. 3, Fasc. 7-9. Muséum National d'Histoire Naturelle, Laboratoire de Phanérogamie, Paris, France.
David J. Middleton. 1999. Flora of Thailand, Vol. 7, part 1. The Forest Herbarium, Royal Forest Department, Bangkok, Thailand.
Gardner S., Sidisunthorn P. & Anusarnsunthorn V. 2000. A field guide to Forest Trees of Northern Thailand. Kobfai Publishing Project.

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