Mitragyna

Family Rubiaceae. Order Rubiales.

Large trees to small trees. Buttresses absent. Spines absent. Stilt roots absent. Bark gray; not peeling in strips. Slash red. Vertical stripes in the inner bark or wood absent. Odor absent. Exudate absent. Terminal buds not enclosed by leaves.

Complex hairs absent. Stinging hairs absent. Mature twig indumentum absent.

Leaves opposite; not scale-like; simple; all of the same type; not modified into spines; coriaceous, or paper-like; not gland-dotted; symmetric at the base; not dissected; smooth margined. Epidermis not waxy. Venation pinnate. Secondary veins open; prominent. Smallest veins prominent to not prominent, but visible; ladder like. Intramarginal vein absent. Stalk of blade less than a quarter the length of the blade to a quarter to one half the length of the blade; not winged; attached to base of leaf blade; not swollen. Stipules present; joined; joined across twigs; encircling the twig; leafy; not fringed; large to small; not persistent. Domatia absent. Basal glands absent. Hairs on mature leaf present, or absent; sparse.

Inflorescences present; terminal; on an unbranched axis; specialized inflorescence units present; specialized inflorescence units heads; numerous and persistent inflorescence bracts absent. Flowers bisexual; not stalked; with the parts barely visible to the eye to about 0.5 cm long or across; round; with male or female parts not raised on a column. Hypanthium absent. Disk present. Perianth present; with distinct calyx and corolla whorls. Sepals 5; partially joined; not persistent in fruit; not growing any further after flowering. Epicalyx absent. Petals present; 5; all joined; not fleshy; deciduous; not stalked; entire. Stamens 5; filaments present; free of each other; joined to the perianth; all equal in size; isomerous; opposite the sepals (when isomerous). Anthers 2 loculed; attached by the base; not awned; dehiscing by long slits. Ovary inferior. Carpels joined; 2. Locules 2. Styles solitary. Stigmas 1 lobed; distinctive; cylindrical with a hollow base. Fruit capsular; non-fleshy; multiple; splitting; not enclosed in, or sitting on, fleshy perianth parts; wingless. Seeds 100 per fruit (many); barely visible; winged; uniform in cross-section; aril absent; endospermic.

Inflorescence a solitary terminal head; stigma mitriform; seeds numerous and winged at both ends. Taxon images: mitrag.gif


Cite this publication as: Jarvie, J.K. and Ermayanti (1996 onwards). `Tree Genera of Borneo - Descriptions and Illustrations' URL http://django.harvard.edu/users/jjarvie/Borneo.htm/.
Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993) should also be cited.