Trigoniastrum

Family Trigoniaceae. Order Polygalales.

Large trees to small trees. Buttresses present, or absent; short. Spines absent. Stilt roots absent. Bark yellow, gray; not peeling in strips. Slash yellow, orange, brown. 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 two-ranked; not scale-like; simple; all of the same type; not modified into spines; coriaceous, or leathery; not gland-dotted; symmetric at the base; not dissected; smooth margined. Epidermis waxy, or not waxy. Venation pinnate. Secondary veins open (very); prominent. Smallest veins prominent, or not prominent, but visible; net like. Intramarginal vein absent. Stalk of blade less than a quarter the length of the blade; not winged; attached to base of leaf blade; not swollen. Stipules present; free from one another; laterally placed; not encircling the twig; scale-like; not fringed; small; not persistent. Domatia present, or absent (lf tp); scattered across lamina. Basal glands absent. Hairs on mature leaf present; dense.

Inflorescences present; terminal, or axillary; on a branched axis; specialized inflorescence units absent; numerous and persistent inflorescence bracts absent. Flowers bisexual; stalked; about 0.5 cm long or across; somewhat asymmetric, or with one plane of symmetry; with male or female parts not raised on a column. Hypanthium absent. Disk present, or absent. Perianth present; with distinct calyx and corolla whorls. Sepals 5; free; not persistent in fruit; not growing any further after flowering. Epicalyx absent. Petals present; 5; free (unequal); fleshy, or not fleshy; deciduous; not stalked; entire. Stamens 6; filaments present; joined; free of the perianth; all equal in size. Anthers 2 loculed; not awned; dehiscing by long slits. Ovary superior. Carpels joined; 3. Locules 3. Styles solitary. Stigmas 3 lobed; not distinctive. Fruit a samara; non-fleshy; not multiple; not splitting; not enclosed in, or sitting on, fleshy perianth parts; winged. Seeds 1-3 per fruit (1 or 3); less than 5 mm; wingless; uniform in cross-section; aril absent; non-endospermic.

Leaves distichous; apex acuminate and usually with large glands; abaxial surface covered in small white hairs; one petal forming a nectar-filled sac; fruits breaking into 3 samaras, the wings large; twig bark often pale white. Taxon images: trigon.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.