Rhamnus

Family Rhamnaceae. Order Rhamnales.

Small trees to shrubs. Buttresses absent. Spines absent. Stilt roots absent. Bark not peeling in strips. Exudate absent. Terminal buds not enclosed by leaves.

Complex hairs absent. Stinging hairs absent. Mature twig indumentum present, or absent; dense, or sparse.

Leaves opposite, or two-ranked; 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, or wavy margined, or with small to large teeth on margin. Epidermis waxy, or not waxy. Venation pinnate. Secondary veins open; prominent, or not prominent, but visible. Smallest veins 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; winged, or 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 present; dense, or sparse.

Inflorescences present; terminal, or axillary; the flowers from a single point on the stem, or on a branched axis; specialized inflorescence units absent; numerous and persistent inflorescence bracts absent. Flowers bisexual; stalked; with the parts barely visible to the eye, or about 0.5 cm long or across; round; with male or female parts not raised on a column. Hypanthium present. Disk present. Perianth present; with distinct calyx and corolla whorls. Sepals 4-5; partially joined; persistent in fruit, or not persistent in fruit; not growing any further after flowering. Epicalyx absent. Petals present, or absent; 4-5; free; not fleshy; deciduous; deeply cut in two, or lobed. Stamens 5; filaments present; free of each other; free of the perianth; all equal in size; isomerous; alternating with the sepals (when isomerous). Anthers 2 loculed; attached along the side; not awned; dehiscing by long slits. Ovary superior. Carpels joined; 3. Locules 3. Styles solitary. Stigmas 3 lobed; not distinctive. Fruit drupaceous; fleshy; not multiple; not splitting; not enclosed in, or sitting on, fleshy perianth parts; wingless. Seeds 1-3 per fruit; barely visible, or less than 5 mm; wingless; uniform in cross-section; aril absent; endospermic.

Leaves distichous; venation pinnate; veins often long and roughly hairy; flowers and fruits small. Taxon images: genrham.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.