| # The Families of Angiosperms |

L. Watson and M.J. Dallwitz

### Trimeniaceae Perk. & Gilg

Habit and leaf form. Trees and shrubs; bearing essential oils. Self supporting, or climbing; the climbers scrambling. Leaves opposite; petiolate; gland-dotted; aromatic, or without marked odour (?); simple. Lamina entire; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins dentate. Leaf development not ‘graminaceous’.

Leaf anatomy. The leaf lamina dorsiventral. Stomata present; paracytic. Adaxial hypodermis absent. The mesophyll with spherical etherial oil cells.

Axial (stem, wood) anatomy. Cork cambium present; initially superficial. Nodes unilacunar (but with two traces). Secondary thickening developing from a conventional cambial ring.

The vessel end-walls scalariform. The axial xylem with fibre tracheids.

Reproductive type, pollination. Unisexual flowers present, or absent. Plants hermaphrodite, or polygamomonoecious, or polygamodioecious.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes, or in racemes, or in panicles. The ultimate inflorescence units cymose. Inflorescences terminal, or axillary; racemes or panicles. Flowers bracteate; bracteolate (the numerous bracteoles passing imperceptibly into the perianth); small; regular; partially acyclic, or acyclic. The androecium acyclic, or the perianth acyclic and the androecium acyclic. Floral receptacle not markedly hollowed (more or less flat).

Perianth sepaline (inseparable from ‘bracteoles’); 10–50 (decussate pairs, or spiral); free.

Androecium in hermaphrodite and male flowers, (7–)10–20(–23). Androecial members maturing centripetally; free of the perianth; free of one another; 2–3 seriate, spiralled. Androecium exclusively of fertile stamens. Stamens in hermaphrodite and male flowers, 7–23; filantherous. Anthers basifixed; non-versatile; dehiscing via longitudinal slits; introrse to latrorse; appendaged (via a shortly produced, tonguelike connective). Pollen shed as single grains. Pollen grains aperturate; 2 aperturate (Piptocalyx), or 8–12 aperturate (Trimenia); more or less foraminate (with two irregular unthickened areas in Piptocalyx, 8–12 foramina in Trimenia).

Gynoecium of female-fertile flowers, 1 carpelled (ostensibly), or 2 carpelled. The pistil 1 celled. Gynoecium monomerous (pseudomonomerous, by abortion?), or syncarpous; of one carpel, or eu-syncarpous; superior. Carpel (if considered monomerous) non-stylate; apically stigmatic; 1 ovuled. Placentation apical. Ovary if considered syncarpous, 1 locular. Gynoecium non-stylate. Placentation apical. Ovules in the single cavity 1; pendulous; non-arillate; anatropous.

Fruit fleshy. The fruiting carpel indehiscent; if considered monomerous, drupaceous. Fruit if considered syncarpous, indehiscent; a drupe (with thin, slimy flesh); 1 seeded (compressed). Seeds endospermic. Embryo straight.

Physiology, phytochemistry. Aluminium accumulation demonstrated. Sieve-tube plastids S-type.

Geography, cytology. Sub-tropical to tropical. Eastern Malaysia, Eastern Australia, Pacific.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Magnoliiflorae; Laurales. Cronquist’s Subclass Magnoliidae; Laurales. APG III peripheral angiosperms; Superorder Austrobaileyanae. APG IV Order Austrobaileyales.

Species 5. Genera 1, or 2; Piptocalyx (= Trimenia), Trimenia.

Illustrations. • Trimenia moorei (as Piptocalyx): Hook. Ic. Pl. 24 (1895). • Trimenia weinmanniflora: 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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