| # The Families of Angiosperms |

L. Watson and M.J. Dallwitz

### Gonystylaceae Van Tiegh

~ Thymelaeaceae.

Habit and leaf form. Trees. Leaves alternate; leathery; petiolate; non-sheathing; gland-dotted (commonly pellucid-punctate), or not gland-dotted; simple. Lamina entire; pinnately veined (with numerous nerves). Leaves exstipulate. Lamina margins entire.

Leaf anatomy. The leaf lamina dorsiventral. Mucilaginous epidermis present. Stomata present; mainly confined to one surface (abaxial); cyclocytic. Hairs present; exclusively eglandular; unicellular. Lamina with secretory cavities. The mesophyll containing crystals. The crystals druses.

Axial (stem, wood) anatomy. Cork cambium present; initially superficial. Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring (with no intraxylary phloem, by contrast with Thymelaeaceae sensu stricto). Primary medullary rays narrow (mostly uniseriate).

The wood diffuse porous. The vessels medium; solitary, radially paired, in radial multiples, clustered, and in tangential arcs (solitary and in multiples of up to 4 cells, sometimes with irregular clusters locally, sometimes tending to oblique patterns). The vessel end-walls simple. The vessels with vestured pits. The axial xylem with tracheids; with fibre tracheids. The parenchyma apotracheal to paratracheal (intermediate). ‘Included’ phloem absent. The wood not storied.

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

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in panicles. The ultimate inflorescence units cymose. Inflorescences terminal. Flowers regular. Free hypanthium present. Hypogynous disk absent.

Perianth with distinct calyx and corolla (unless the ‘corolla’ of Hutchinson, Cronquist et al. is interpreted as an extrastaminal disk, as by Airy Shaw 1973); 12–45; anisomerous. Calyx 5; 1 whorled; polysepalous, or gamosepalous (?); five blunt-lobed; regular; imbricate. Corolla 7–40; polypetalous (the petals 7–40, linear or deltoid, sometimes divided almost to the base, inserted on the hypanthium). Petals deeply bifid, or entire.

Androecium (8–)30–100 (usually ‘many’). Androecial members free of the perianth; free of one another. Androecium exclusively of fertile stamens. Stamens (8–)30–100 (usually ‘many’); polystemonous; filantherous. Anthers basifixed; non-versatile; dehiscing via longitudinal slits. Pollen grains aperturate; 4–11 aperturate (?); (oligo-) foraminate.

Gynoecium 3–5 carpelled. Carpels reduced in number relative to the perianth to isomerous with the perianth. The pistil 3–5 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 3–5 locular. Gynoecium stylate. Styles 1; apical; much longer than the ovary (threadlike, bent). Stigmas 1; small. Placentation apical. Ovules 1 per locule; pendulous; arillate.

Fruit non-fleshy (thick walled, becoming woody); tardily dehiscent; a capsule. Capsules loculicidal. Fruit 1–3 seeded. Seeds non-endospermic; large. Embryo straight.

Geography, cytology. Paleotropical. Tropical. Malaysia.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Malviflorae; Thymelaeales. Cronquist’s Subclass Rosidae; Myrtales. APG III core angiosperms; core eudicot; Superorder Rosanae; malvid. APG IV Order Malvales (as a synonym of Thymelaeaceae).

Species 30. Genera 1; (?)only genus, Gonystylus.

General remarks. Seeming to differ from Thymelaeaceae in habit, inflorescence and fruit form, as well as in recorded data on leaf and wood anatomy.

Economic uses, etc. Timber tree — ramin.

Illustrations. • Gonystylus bancanus: Atlas der Baumgarten Java 2 (1914). • Gonystylus miquelianus (Hutchinson).

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: 8th June 2026. delta-intkey.com’.

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