Dillenia L.

Trees or rarely shrubs, mostly evergreen (rarely deciduous), sometimes buttressed, rarely with stilt-roots, glabrous or with simple hairs; bark red, grey or brown, peeling as thin, often papery flakes. Leaves alternate and spirally arranged, simple, petiolate; petiole channelled above, with or without narrow to broad amplexicaul wings that are caducous or persistent; lamina often elliptic or ovate to obovate, often large; margin entire to distinctly dentate or undulate; venation of several to numerous veins, usually prominent on both surfaces (more so beneath); apex usually obtuse or rarely acute, sometimes apiculate or acuminate; leaves of saplings and young trees often larger and sometimes differing in shape from those on older growth. Inflorescences terminal or ± leaf-opposed, comprising a solitary flower or few (–30)-flowered cincinnus, thyrsoid or panicle; bracts absent to many, often caducous. Flowers actinomorphic, often large, pedicellate; bracteoles absent to several, usually inconspicuous. Sepals (4) 5 (–18), ± equal or unequal, free, imbricate, persistent in fruit. Petals (4) 5 (–7) or rarely absent, free, imbricate, elliptic to obovate, yellow or white, rarely remaining closed. Stamens usually very numerous, surrounding the gynoecium; stamens ± equal in length or inner stamens with anthers longer and sometimes differing in colour from the outer; anthers opening by apical or subapical pores or rarely longitudinal slits; staminodes often numerous, free or slightly to distinctly coherent, shorter or longer than the stamens, outside (or very rarely inside) the fertile stamens. Carpels (4) 5–15 (–20), basally coherent; styles horizontally spreading to nearly erect, stigmas usually expanded or rarely capitulate; ovules 4–80 per carpel; placentation marginal with ovules in 2 (4) vertical rows. Fruit a dehiscent aggregate of basally coherent follicles opening along the adaxial suture (the calyx and carpels appearing star-like), or indehiscent and enclosed by the fleshy, accrescent sepals; seeds endospermic, with a fleshy to membranous aril, varying in size from completely enclosing the seed minutely cup-like at the base, white or bright red; embryo minute.

Most species occur in evergreen forests on dry to very wet soil. Some deciduous species are found in monsoon forests or savannahs, one evergreen species in savannahs of New Guinea and N. Australia. As to altitudinal distribution the species generally occur below 1000 m, but some are occasionally found above this altitude, up to 2000 m; one species (D. montana DIELS) has been collected only above 1000 m.Stilt-roots occur constantly only in a few species, vizD. borneensis HOOGL., D. eximia MIQ., and D. reticulata KING; in a few others they may be occasionally developed, e.g. in D. papuana MARTELLI and D. albiflos (RIDL.) HOOGL.The leaves of saplings and young plants are often considerably larger than those of the full-grown plants. In most cases these leaves are relatively narrower, without showing a distinct dimorphism. In D. ferruginea (BAILL.) GILG from the Seychelle Islands, however, a distinct leaf-dimorphism is found between these leaves. In a less degree this is found in Malaysia in D. pentagyna ROXB. and probably in D. pteropoda (MIQ.) HOOGL.In some species the petals drop without having opened in anthesis. In Malaysia this is found only in D. papuana MARTELLI and some other New Guinean species.The dispersal of fruits and seeds is effected mainly by animals. The indehiscent fruits would be eaten mainly by mammals, the arillate seeds of the species with dehiscent fruits by birds. Transport by water is a means of dispersal in D. indica L.

Uses. Though sometimes used for light constructions, the wood is generally of low value because of the short durability. D. pentagyna ROXB. is used for making a charcoal of good quality.The indehiscent fruits of some species are eaten, in particular in curries and jellies; they have an acid taste. Mixed with syrup they make a cough cure, and they are sometimes used for washing the hair.Because of the beautiful flowers and foliage a number of species are suitable as ornamental trees or shrubs, e.g. D. indica L., D. philippinensis ROLFE, and D. sujfruticosa (GRIFF.) MARTELLI.