Hopea Roxb.

Timothy M. A. Utteridge and Laura V. S. Jennings (2022). Trees of New Guinea. Kew Publishing. Royal Botanic Gardens, Kew

Distribution

As currently defined, Hopea is a genus of about 100 species ranging from Sri Lanka to New Guinea; 13 species in New Guinea, 11 endemic.

Morphology General Habit

Canopy and sub-canopy trees to 50 m, often with narrow buttresses or stilt roots

Morphology Leaves Stipules

Stipules linear, falling early. Leaves without an intramarginal vein, other venation variable

Morphology Reproductive morphology Inflorescences

Inflorescences terminal or axillary, paniculate, one-sided, slender

Morphology Reproductive morphology Flowers

Flowers with ovoid buds; sepals imbricate, 2 outer lobes thickened, obtuse, 3 inner lobes thin at the margins, mucronate; petals oblong, contorted, fused at the base, falling in a rosette; stamens 10 or 15 (in New Guinea), adnate to petals and falling with them, anthers subglobose, connectival appendage slender, at least twice the length of the anthers; ovary stylopodium indistinct or distinct, style long or short, stigma minute

Morphology Reproductive morphology Fruits

Fruit a small ovoid nut, calyx lobes imbricate, 2 sepals becoming prolonged, forming ‘wings’, 3 sepals short or 5 short, subequal lobes.

Ecology

Hopea have been collected from primary and secondary forests, including swamp forest, from sea level to c. 520 m.

Recognition

In New Guinea, Hopea is distinguished from other dipterocarp genera by the one-sided inflorescence, the petals and stamens that fall as a unit, and the imbricate fruit calyx lobes. The flowers of some species have been described as having a sweet but unpleasant odour.