Pterocymbium

Family Sterculiaceae. Order Malvales.

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

Complex hairs present; star-like. Stinging hairs absent. Mature twig indumentum absent.

Leaves spiral; not scale-like; simple; all of the same type; not modified into spines; coriaceous; not gland-dotted; symmetric at the base; not dissected; smooth margined. Epidermis waxy, or not waxy. Venation trinerved, or palmate. Secondary veins open; prominent. Smallest veins prominent, or not prominent, but visible; net like, or ladder like. Intramarginal vein absent. Stalk of blade a quarter to one half the length of the blade to more than half 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 absent. Basal glands absent. Hairs on mature leaf absent.

Inflorescences present; terminal; on a branched axis; specialized inflorescence units absent; numerous and persistent inflorescence bracts absent. Flowers at least some flowers unisexual; with male and female flowers on the same plant; stalked; about 0.5 cm long or across to to about 3 cm long or across; round; with male or female parts raised on a column; with male and female parts raised on a stalk. Hypanthium absent. Disk present; the stamens inside the disk. Perianth present; with distinct calyx and corolla whorls. Sepals 5; partially joined; persistent in fruit; not growing any further after flowering. Epicalyx absent. Petals absent. Stamens 10; filaments present; joined; free of the perianth; all equal in size; diplostemonous. Anthers 2 loculed; attached along the side; not awned; dehiscing by long slits. Ovary superior. Carpels joined, or partially joined, by base; 3-6. Locules 3-6. Styles free; 3-6. Stigmas 1 lobed; not distinctive. Fruit follicular; non-fleshy; not multiple; splitting; not enclosed in, or sitting on, fleshy perianth parts; winged. Seeds 1 per fruit; less than 5 mm to about 1 cm long; wingless; uniform in cross-section; aril absent; endospermic.

Bole with wart-like projections; calyx persistent; carpels splitting to form follicles; follicles with large wings - to about 10 cm long.


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.