Mitragyna stipulosa (DC.) Kuntze

Mitragyna stipulosa (DeCandolle) O. Kuntze

Standard trade name: Abura

Local name: Subaha

A swamp forest tree up to 100 ft tall, sometimes of vast size; leaves simple, opposite with interpetiolar stipules; flowers small, scented; sapwood white, heartwood pinkish yellow, moderately hard and straight-grained.

GENERAL DESCRIPTION.—It is a light-weight wood, average weight being about 35 lb/ft 3 seasoned. Its green weight averages about 55 lb/ft3. The color of the wood is light yellowish brown or pinkish brown. It has moderately straight or interlocked grain and even texture.

SEASONING.—Abura seasons rapidly and well without any degrade. British Forest Products Laboratory kiln schedule K is strongly recommended (FPRL, 1956).

DURABILITY.—It is not durable. It is moderately resistant to preservative treatment; the sapwood, however, is permeable.

WORKING QUALITIES.—This timber usually works well with hand and machine tools but has a variable dulling effect on cutting edges. For a good finish, then, sharp cutting edges should be employed. It stains and polishes well and takes light nails satisfactorily.

USES.—Abura is used for light construction work. Since it is acid resistant, it is used for battery boxes as well as laboratory fittings, brick backs, and some classes of pattern making.

XYLEM ANATOMY.—Growth rings absent. Wood diffuse-porous. Vessels: mostly paired but also solitary and in radially oriented (occasionally tangential) groups of 3 to 5; mostly oval pore openings but sometimes circular or somewhat angular; average radial pore diarneter 60μm, range 40μm–70μm; average tangential pore diameter 80μm, range 55μm–105μm; average vessel element length 608μm, range 275μm–913μm; vessel wall thickness 3μm; perforation plates not seen; vessel element end wall inclination 15° to 45° from horizontal; intervascular pitting alternate. Imperforate tracheary elements: nonseptate fiber tracheids, average length 1701μm, range 963μm–2313μm; fiber tracheids with slitlike pits on radial and tangential walls, slits slightly inclined from the horizontal. Vascular rays: heterogeneous; largely multiseriate, only a few uniseriate rays seen; mostly 2 (sometimes 3) cells wide, 9 to 49 cells high excluding uniseriate and biseriate tails; tails 2 to 6 cells high, occasional multiseriate rays divided near middle by uniseriate row of ray cells; ray cells in part occluded with dark amorphous material. Axial parenchyma: apotracheal, diffuse, isolated or in small groups of radially oriented cells.

RUBIACEAE (NAUCLEACEAE)