Dipterocarpaceae

Small or large resinous usually evergreen trees, usually buttressed, and often (if large trees) with flaky or fissured bark. Some or most parts with a tomentum of fascicled hairs, or sometimes single hairs, unicellular or multicellular glandular hairs, or multicellular, short or long lobed or peltate hairs. Leaves alternate, simple, margin entire or sinuate, not crenate, terminating ± abruptly at the ± prominent geniculate petiole, penninerved (in Dryobalanops and some Hopea nerves ~, dense and slender), often with domatia in axils between nerves and midrib or along midrib and (rarely) nerves; tertiary nerves scalariform or reticulate. Stipules paired, large or small, persistent or fugaceous, leaving small to amplexicaul scars. Inflorescence paniculate, racemose, rarely cymose, ± regularly, rarely irregularly, branched, terminal or axillary; bracts and bracteoles paired, small or large, persistent or fugaceous. Flowers secund or distichous, bisexual, actinomorphic, scented, nodding. Calyx persistent, 5-merous; 2-5 sepals usually greatly enlarging into wing-like lobes in fruit; sepals either free to base, imbricate in bud, remaining so or becoming valvate in fruit, or fused at base, forming a cup or tube ± enclosing the fruit, adnate to or free from it. Corolla 5-merous, contorted, base connate or free, usually partially or entirely unicellular hairy. Stamens 5-110, 1-3 verticillate or irregular, hypogynous or subperigynous, centrifugal; filaments compressed or filiform, free or connate, frequently cohering with petals on falling; anthers erect, 2-celled with (2-)4 pollen sacs, introrse or laterally dehiscent; tapetal cells binucleate, pollen grains 2-celled at anthesis; connective with short or prominent appendage. Ovary superior or semi-inferior, 3-, rarely 2-, locular; style ± thickened at base into a stylopodium, entire or trifid towards apex; stigma obscure or prominent, 3- or 6-lobed. Ovules 2(-3) in each loculus, axile, pendulous or laterally anatropous, bitegmatic with ventral raphe and superior micropyle. Fruit indehiscent, 1-seeded; with woody pericarp and persistent ± aliform sepals. Embryo-sac development of Polygonum type: endosperm of the nuclear type, embryo development normal, ripe seeds with or more usually without endosperm; cotyledons equal or more usually unequal and with one more or less enclosing the other, laminar or fleshy, entire or lobed, enclosing the radical. Germination epigeal or hypogeal; pericarp splitting irregularly or along 3 sutures. Distribution. The newly described monotypic genus Pakaraimaea MAGUIRE & ASHTON (1977), locally found in the south of former British Guyana, makes the family pantropical, confined to the lowlands and hills of the tropics below 1800 m. Fig. 2. This genus represents a distinct subfamily Pakaraimoideae.