Family Trimeniaceae

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. Leaves without a persistent basal meristem.

Leaf anatomy. Stomata present; paracytic.

Adaxial hypodermis absent. Lamina dorsiventral. The mesophyll with spherical etherial oil cells.

Stem anatomy. Cork cambium present; initially superficial. Nodes unilacunar (with two traces). Secondary thickening developing from a conventional cambial ring. Xylem with fibre tracheids. Vessel end-walls scalariform. Sieve-tube plastids S-type.

Reproductive type, pollination. 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 unit 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 (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 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 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, biochemistry. Aluminium accumulation demonstrated.

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 3 peripheral angiosperms; Superorder Austrobaileyanae; Order Austrobaileyales.

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