Carya tonkinensis Lecomte - JUGLANDACEAE

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Botanical descriptions Habitat and ecology Distribution

Botanical descriptions :

Diagnostic characters : Leaves imparipinnate, alternate and spiral, rachis with glands. Flowers unisexual, catkins. Fruits a winged nut.
Habit : Deciduous tree up to 25 m tall. Branches ascending to the main trunk and branches ramification from the base.
Trunk & bark : Trunk straight. Bark fissured, lenticelled, grey-brown or dark grey, inner bark yellowish orange and very hard.
Branches and branchlets or twigs : Twigs terete, lenticelled, glabrous, dark brown or greenish brown, with leaf scars. Young twigs covered with glandular scales, orange red, becoming dark brown drying with scattered stellate hairs.
Exudates : Exudate absent.
Leaves : Leaves compound, imparipinnate, alternate spiral, rachis 10-25 cm long , 5-7 opposite leaflets, 6-15 by 2.7-5.2 cm, ovate, sometimes obovate, apex acute, acuminate, base rounded, margin serrulate, blade thin papery, glabrescent along the midrib, scattered glandular scales on both sides.
Midrib flat above, primary vein single, pinnate, secondary veins oblique to the midrib, widely parallel, tertiary veins oblique. Rachis densely covered with orange glandular scales with stellate yellow hairs, becoming glabrous when mature.
Stipules absent.
Inflorescences or flowers : Flowers unisexual, male and female flowers green, grouped in separated lateral catkins, usually males catkins grouped by 2 to 3, female with conspicuous perianth.
Fruits : Fruit is a winged nut, 3 x 2.8 cm, compressed subglobose, dehiscent by 3-4 valves.
Seeds : 1 seed.

Habitat and ecology :

In secondary or regenerated forest up to 1200 m altitude, well developed in moist and well-drained soil. Flowering from March to May, fruiting from July to September.

Distribution :

India (Assam), China (Yunnan, Guangxi), Vietnam (Northern) and Laos (Bolikhamxay province).

Remark/notes/uses :
The nuts are sometimes collected for their oil which is used for lighting and cooking. The bark gives a brown dye and is made into a tea and given to women after childbirth to contract the uterus and reduce bleeding. Pink, heavy and good wood, is used for construction, furniture. Seeds edible, can be pressed for oil.

Specimens studied :
BT 393 (Herbarium of Faculty of Sciences-NUoL, NHN-Leiden and CIRAD-Montpellier).

Literature :
Dung, Vu Van. 1996. Vietnam Forest Trees. Agriculture Publishing House, Hanoi, Vietnam.
Flore Générale de l’Indochine. 1929. Vol. 5, Fasc. 8-10. Muséum National d'Histoire Naturelle, Laboratoire de Phanérogamie, Paris, France.
Pham Hoang Ho.1992. Flore du Cambodge, Laos et Vietnam, No 26. Museum National d’Histoire Naturelle.

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