Volume 15 > Part 1 > Year 2021 > Page 91 > Rubiaceae > Mitragyna

4. Mitragyna speciosa (Korth.) Havil.wfo-0000244943

J. Linn. Soc. Bot. 33: 69. 1897; Ridl., Fl. Malay Penins. 2: 6. 1923; Craib, Fl. Siam. 2: 14. 1932; Ridsdale in Blumea 24: 65. 1978.— Stephegyne speciosa Kort., Verh. Nat. Gesch. Ned. Bezitt. 2, Bot.: 160, t. 35. 1840.— Nauclea speciosa (Kort.) Miq., Fl. Ned. Ind. 2: 140. 1857, nom. illeg. [non Nauclea speciosa (Wall. ex G.Don.) Walp., 1843]. Plate VIII: B–C.

Accepted Name : This is currently accepted.

Description : Briefly deciduous (sometimes evergreen?) trees to 25 m tall; bark grey to greyish brown, smooth; terminal vegetative bud lanceolate in outline, flattened. Stipules lanceolate, to 4 by 1 cm, keeled. Leaves elliptic to slightly ovate or obovate, 5–17 by 3–12 cm, base rounded to cordate, apex acute, chartaceous to subcoriaceous, glabrous above and below or slightly hairy on lower surface only, lateral veins (8–)11–17 pairs, relatively ‘flat’ (angle between midrib and veins 20–60°), pale hairy domatia present in vein axils; petiole (1–)2.5–5 cm long. Inflorescences terminal, solitary; pedunculate flowering heads, pale-hairy; spathulate interfloral bracteoles 4–6 mm long, longer than ovary plus calyx (hence calyces concealed by interfloral bracteoles in your flowering heads). Flowering heads 0.9–1.3 cm across interfloral bracteoles, 1.5–2.5 cm across corollas. Calyx sometimes pinkish; tube to 2 mm long; lobes hardly developed. Corolla creamy white to yellowish white, turning darker with age; tube 3.5–5 mm long, outside glabrous, inside densely hairy, hairs protruding from throat; lobes 2.5–3 mm. Stamens subsessile; anthers 1–1.5 mm long, exserted from throat, spreading. Ovary 1.5–2 mm high, glabrous; style plus stigma exserted for 3–5 mm; stigma 1–2 mm long. Fruiting heads 2–3 cm in diam. Fruitlets 7–9 mm long, glabrous, crowned by persistent calyx.

Thailand : CENTRAL: Krung Thep Maha Nakhon (Bangkok), cultivated; SOUTH-WESTERN: Ratchaburi; PENINSULAR: Phangnga.

Distribution : Vietnam (cultivated), Peninsular Malaysia, Sumatra, Borneo (type), the Philippines, New Guinea.

Ecology : Mostly in lowland evergreen forests, often in moist to wet places along streams, occasionally also in swamp forests, to 200 m alt.

Vernacular : Kra thom (กระท่อม), i thang (อีถ่าง)(Central); thom (ท่อม)(Peninsular).

Uses: Various traditional uses: to treat diarrhea; as a stimulant; as an opium substitute. In recent years Kratom has gained popularity as recreational drug, due to its narcotic like effects, producing feelings of euphoria similar to heroin. Typically, fresh leaves are chewed, but dried leaves are sometimes smoked or made into powder and drunk as tea [see http://www.mitragyna.com/index.php].

Notes: Although frequently cultivated in the Peninsula, the species also occurs naturally.