Trimenia

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Trimenia

Description

Small trees, shrubs or lianas, up to 20 m or more, young parts tomentose or glabrous. Leaves opposite, petiolate, exstipulate, ovate to ovate-lanceolate (obovate, extra-Mal.), base cuneate, apex acute to long acuminate, entire or ser-rate, with translucent dots, nerves connected near the margin. Inflorescence axillary or terminal, cymose, pleiochasial (racemose) or paniculate. Flowers unisexual or bisexual; Stamens 7-25, spirally arranged, filament shorter or as long as the anther, connective produced at apex, anthers tetrasporangiate, extrorse or latrorse, opening by two longitudinal slits. Fruit a small spherical, succulent berry. Seed hard, smooth or ridged;

Distribution

Asia-Tropical:, Maluku (Malukupresent); New Guineapresent Australasia:, New South Wales (New South Walespresent) Batjan: present Bougainville: present Central Celebes: present Ceram: present E. Australia: present Eastern Pacific: present New Britain: present New Caledonia: present New Ireland: present Pacific:, Fiji (Fijipresent); Marquesas (Marquesaspresent); Samoa (Samoapresent) Polynesia: present Solomons: present
Eastern Pacific (Marquesas), Polynesia (Samoa, Fiji), New Caledonia, E. Australia (New South Wales), Solomons (Bougainville) and Malesia: New Guinea (incl. New Britain&New Ireland), Moluccas (Ceram, Batjan) and Central Celebes. In all 5 spp. .

Dispersal

The one-seeded succulent fruit has dark red to purple juice, and no doubt is distributed by birds.

Morphology

The leaves are in decussate pairs and exstipulate. The lamina is tapered to an acute apex which in T. macrura is elongated into a delicate drip-tip. Inflorescences are lateral, or in some species also terminal. The inflorescence axes bear a terminal flower and either pairs of opposite flowers or branches which in turn bear a series of flower pairs, or even branches of a third order, when the inflorescence becomes a diffuse panicle.

Anatomy

Anatomical features are described by MONEY, BAILEY & SWAMY (1950), METCALFE & CHALK (1950), RODENBURG (1971) and CARLQUIST (1984). Hairs are unicellular or tricellular uniseriate and non-glandular. Stomata are paracytic. Oil cells and mucilage cells occur in the mesophyll of the leaf and in the axis. The leaf blade has no hypodermis and a palisade layer is not clearly defined from the spongy mesophyll. The leaf trace which departs from the single nodal gap comprises 2 or 4 bundles. Young stems develop no hippocrepiform sclereids (or only vestiges of them) in the pericycle opposite the interfascicular sectors. Elongated sclereids develop precociously in the secondary phloem. In the secondary xylem the vessel elements are long with high incidence of scalariform intercellular pitting. There are numerous uniseriate rays in addition to multiseriate rays (5 or 6 cells wide). Gelatinous fibres occur in the tension wood (KUČERA & PHILIPSON, 1977). Phloem plastids are of the S-type (BEHNKE, pers. comm.).

Cytology

Trimenia papuana (GOLDBLATT, 1974) and T. moorei (GOLDBLATT & BRIGGS, 1979) both give counts of n = 8.

Phytochemo

The lignans (or neolignans) veraguensin and calopiptin have been isolated from Trimenia papuana and Piptocalyx (= Trimenia) moorei ('bitter vine') respectively. The nature of the bitter principles of bitter vine is still unknown, but a slightly sweet glucoside was isolated from its leaves and called piptoside; its aglucone was shown to be structurally related to the proteaceous metabolite leucodrin. CHENERY reported aluminium accumulation for one species of Trimenia (two investigated), but not for Piptocalyx (one species tested). The lack of benzylisoquinoline alkaloids in Trimeniaceae conforms with the exclusion of the taxon from Monimiaceae.
family treated together with Monimiaceae — R. HEGNAUER.

Citation

PAX - in E. & P., Nat. Pfl. Fam. 3. 1889: 98
PERKINS & GILG - in Pfl. R. 1901: f. 4d-f.
B. & H. - in Gen. Pl. 1880: 143
RODENBURG - in Blumea. 1971: 3
GIBBS, Arfak. 1917: 135
PERKINS, Übersicht Gattungen Monim. 1925: 22
PERKINS & GILG - in Pfl. R. 1901: f. 4a-c
SEEMANN - in Bot. Jahrb. 1923: f. 1
A.C. SMITH - in J. Arn. Arb. 1942: 442
RIDL. - in Trans. Linn. Soc. Bot. 1916: 144
GILG & SCHLTR - in Bot. Jahrb. 1919: f. 1-2