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The families of flowering plants

L. Watson and M.J. Dallwitz

Dipterocarpaceae Bl.

Including Monotaceae (E. Gilg) Maury ex Takhtajan

Habit and leaf form. Trees (often tall with buttressed bases, constituting the ‘mixed Dipterocarp’ forests dominant in Asian lowland rainforests); resinous (Dipterocarpoideae), or not resinous; leptocaul. Mesophytic. Leaves evergreen; alternate; leathery; petiolate (the petiole often geniculate or sinuate); not gland-dotted; simple. Lamina entire; usually prominently pinnately veined; cross-venulate. Leaves stipulate. Stipules intrapetiolar; free of one another; caducous, or persistent. Lamina margins entire. Domatia occurring in the family (from 4 genera and numerous species); manifested as pits (all).

Leaf anatomy. The leaf lamina dorsiventral. Epidermis with crystal idioblasts, or without crystal idioblasts. Mucilaginous epidermis present, or absent. Stomata mainly confined to one surface (abaxial); surrounded by more or less distinct subsidiaries, sometimes paracytic. Hairs present (glandular and eglandular, of diverse forms). Lamina with secretory cavities (often with canals in the vascular system), or without secretory cavities. Secretory cavities when present, containing resin. The mesophyll containing mucilage cells, or not containing mucilage cells; usually containing crystals. The crystals druses (mostly), or raphides (less common).

Axial (stem, wood) anatomy. Secretory cavities always present (as canals, in the pith); with resin, or with resin and with mucilage. Cork cambium present; initially superficial. Nodes tri-lacunar, or penta-lacunar. Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles present (very commonly, concentric or moon-shaped, each with a resin canal in the xylem), or absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring.

The wood diffuse porous. The vessels small to large; solitary, or radially paired, or in radial multiples, or clustered, or in tangential arcs. The vessel end-walls horizontal, or horizontal to oblique; simple. The vessels consistently with vestured pits; without spiral thickening. The axial xylem with tracheids; commonly with vasicentric tracheids, or without vasicentric tracheids; with fibre tracheids; without septate fibres. The fibres without spiral thickening. The parenchyma apotracheal, or paratracheal, or apotracheal and paratracheal. The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones. ‘Included’ phloem absent. The wood not storied.

Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite. Pollination entomophilous.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes (rarely), or in racemes, or in panicles (usually). Inflorescences terminal, or axillary. Flowers bracteate (the bracts caducous); large (showy); often fragrant; regular; 5 merous; cyclic, or partially acyclic. Sometimes the androecium acyclic (the stamens then somewhat irregularly disposed). Floral receptacle developing an androphore (Monotoideae), or with neither androphore nor gynophore (Dipterocarpoideae).

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; polysepalous, or gamosepalous (frequently with a short or long tube); blunt-lobed. Calyx lobes markedly shorter than the tube to markedly longer than the tube. Calyx regular; persistent; accrescent (some or all of the sepals becoming enlarged to constitute a winged fruit); imbricate, or valvate. Corolla 5; 1 whorled; polypetalous, or gamopetalous (the petals often connate at the base). Corolla lobes markedly longer than the tube. Corolla contorted (spirally twisted in bud).

Androecium (5–)15(–100). Androecial members branched (typically with 10 trunk bundles); when many, maturing centrifugally; adnate (often, to the base of the corolla), or free of the perianth; free of one another, or coherent (usually, the filaments connate below); 1–3 whorled (or irregularly disposed). Androecium exclusively of fertile stamens. Stamens (5–)15(–100); isomerous with the perianth to polystemonous. Anthers dorsifixed (Monotoideae), or basifixed (Dipterocarpoideae); dehiscing via longitudinal slits; tetrasporangiate; usually appendaged. The anther appendages apical (the connective extended into a sterile tip to the anther). Endothecium not developing fibrous thickenings. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral, or decussate. Anther wall initially with more than one middle layer; of the ‘dicot’ type. Tapetum glandular. Pollen grains aperturate; 3 aperturate; colpate, or colporate; 2-celled.

Gynoecium 2–3(–5) carpelled. Carpels reduced in number relative to the perianth to isomerous with the perianth. The pistil 2–3(–5) celled. Gynoecium syncarpous; synovarious, or synstylovarious; superior, or partly inferior (Anisoptera). Ovary 2–3(–5) locular. Gynoecium stylate. Styles 1, or 3; when 3, free to partially joined; apical. Stigmas 3 lobed, or 6 lobed. Placentation axile to apical. Ovules 2–4 per locule; pendulous (or laterally attached); more or less epitropous; with ventral raphe; anatropous; bitegmic; crassinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids hooked. Endosperm formation nuclear. Embryogeny asterad (or by irregular cleavage).

Fruit non-fleshy; tardily dehiscent, or indehiscent (usually); commonly conspicuously winged by the accrescent calyx, capsular-indehiscent, or a capsule, or a nut (usually). Capsules when capsular/dehiscent, splitting irregularly, or valvular (then the pericarp splitting into three valves). Fruit 1 seeded. Cotyledons 2. Embryo chlorophyllous (5/6).

Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, phytochemistry. Not cyanogenic. Alkaloids absent (?). Anthraquinones detected (Vatica); polyacetate derived. Iridoids not detected. Saponins/sapogenins absent. Proanthocyanidins present, or absent; when present, cyanidin and delphinidin. Flavonols present, or absent; kaempferol, or myricetin, or quercetin and myricetin, or kaempferol, quercetin, and myricetin. Ellagic acid present (6 genera, 8 species), or absent (3 genera, 3 species). Ursolic acid present. Aluminium accumulation not found.

Geography, cytology. Paleotropical (mostly), Neotropical (Pakaraimaea). Tropical. Palaeotropical, chiefly Indomalayan. X = 6, 7, 10, 11.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Malviflorae; Malvales. Cronquist’s Subclass Dilleniidae; Theales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; malvid; Order Malvales.

Species 580. Genera 17; Marquesia and Monotes (Africa); Anisoptera, Balanocarpus, Cotylelobium, Dipterocarpus, Dryobalanops, Hopea, Neobalanocarpus, Parashorea, Shorea, Stemonoporus, Upuna, Vateria, Vateriopsis, Vatica (Indomalayan); Pakaraimaea (Guayana).

Illustrations. • Technical details: Dipterocarpus, Dryobalanops (Lindley). • Vateria indica: R. Wight (1840). • Vatica ridleyana: Hook. Ic. Pl. 25 (1896). • Vateriopsis seychellarum, as Vateria: Hook. Ic. Pl. 28 (1903). • Hopea ponga (as wightiana): R. Wight (1840). • Shorea rigida: Hook. Ic. Pl. 25 (1896).

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 20th July 2017.’.