Meliosma

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Meliosma

Description

Evergreen or sometimes deciduous shrubs or trees, up to 42 m, 1 m diam., sometimes buttressed. Leaves simple or imparipinnate with (sub)opposite leaflets, ending in 3 or 1 leaflet(s), in the latter case its petiolule articulated with the rachis; Inflorescence terminal, sometimes axilláry, a pyramidal panicle, poor to usually profuse, up to 4 times ramified, with alternate, articulately attached, often lenticellate axes. Flowers numerous, sessile or short-pedicelled, small, bisexual. Sepals 5, by reduction sometimes 4, rarely 3, sometimes by addition of empty bracts seemingly more, up to c. 13, and together forming a kind of involucre, usually unequal and then mostly 3 about equal. Petals 5, episepalous, 3 outer ones more or less unequal, alternisepalous, mostly suborbicular and convex, rarely the largest one much wider than long and more or less reniform, the smaller ones irregularly shaped; Stamens 5, epipetalous, 2 fertile, filament short, strap-shaped, flat, incurved at the top, abruptly terminating in a wide, varyingly shaped cup which bears two globose to elliptic transversely dehiscent anther-cells which are ripe in bud, springing back elasti-cally when the flower opens; Ovary globose to ovoid or conical, 2-, very rarely 3-locular, apically contracted in a rather short, simple or 2-partible, cylindric or subulate to conical, rarely minute style, with simple or somewhat bifid, minute stigma. Ovules 2 (or 1) in each cell, more or less superimposed, attached to the partition, hemi-anatropous. Fruit a drupe, subglobose to pyriform, small, glabrous, with one stone; Seed sub- to semiglobose, more or less concave at the ventral side, with membranous testa, without endosperm.

Distribution

Asia-Temperate: Asia-Tropical: Central and South America: present New World: present present Northern America: SE. Asia: present
About 20-25 species, 15 of which in SE. Asia, and not more than c. 10 in Central and South America. In Malesia: 8 species.
The New World species belong to Meliosma subg. Meliosma sect. Lorenzanea, a section restricted to the New World; besides, there is one species of subg. Kingsboroughia which is widely spread in China but also occurs in Mexico (M. alba WALP.).

Morphology

Trees, mostly small, sometimes shrubs, rarely mentioned to be subscandent, but M. pinnata subsp. ferruginea and subsp. macrophylla are recorded to reach 42 m height and M. lanceolata to reach 30 m by 1 m diam.

The margin of leaf or leaflet may be entire or dentate and is often variable. In saplings, watershoots and seedlings the margin is mostly dentate. In species with pinnate leaves the size of the leaflets mostly increases apically and their greatest width tends to shift towards the upper half. The leaves, when pinnate, have 1 or 3 top-leaflets; in the first case the petiolule of the top-leaflet has an articulation with the rachis.

The inflorescence consists of a racemosely arranged, rich-flowered panicle.

VAN BEUSEKOM ) amply discussed the peculiar flower structure. Although BAILLON assumed the flower to be basically 3-merous, he agrees with the majority of authors that it is 5-merous. The 3 outer petals are differently shaped from the 2 inner ones; the latter may be of the lanceolate or bifid type, and taxonomically their shape is important.

The structure of endocarp and seed () is of great importance. The ovary contains 4 ovules but only one develops into a seed (exceptionally 2, resulting in an anomalous didymous fruit). The fruit is a drupe with rather thin, pulpy mesocarp and a stony to crustaceous endocarp, more or less globular to pyriform, smooth or often with a reticulate surface. When dehiscent, it splits into two valves, the plane of dehiscence usually marked by a ± prominent keel running all around the endocarp. At the ventral side there is a usually narrow pore through which the seed is connected with the vascular bundle towards the pedicel. There are two main types: 1) endocarps which only enclose the seed, whereas the vascular bundle connecting pedicel and seed is running outside the endocarp wall; 2) endocarps which enclose both seed and vascular bundle, the latter being situated in a marginal canal inside.

Taxonomy

The subdivision of the genus Meliosma is as follows:

Citation

WALP. - in Ann. 1852: 834
VAN BEUSEKOM - in Blumea. 1971: 355
MIQ. - in Fl. Ind. Bat. 1859: 612
ROXB. - in Pl. Corom. 1820: t. 254
BENTH. & HOOK.f. - in Gen. Pl. 1862: 414
BOERL. - in Handl. Fl. Ned. Ind. 1890: 290
BLUME - in Rumphia. 1849: 196
HOOK.f. - in Fl. Brit. India. 1876: 3
WARB. - in E. & P., Nat. Pfl. Fam 3. 1895: 371