Combretum Loefl.

Timothy M. A. Utteridge and Laura V. S. Jennings (2022). Trees of New Guinea. Kew Publishing. Royal Botanic Gardens, Kew

Distribution

A genus of about 300 species, with a pantropical distribution and the centre of diversity in Africa. Five species in New Guinea, including Combretum indicum (L.) DeFilipps, formerly placed in Quisqualis L.

Morphology General Habit

Shrubs, often scrambling or climbing. Leaves opposite or whorled, rarely alternate, entire, frequently hairy or scaly but may be glabrous; petioles may persist after leaf fall

Morphology Reproductive morphology Inflorescences

Inflorescences axillary or sub-axillary racemes or spikes, elongated or subcapitate

Morphology Reproductive morphology Flowers

Flowers bisexual, 4- or 5-merous; calyx forming a tube, partly fused to ovary, calyx lobes inconspicuous; petals usually small, may be absent, but showy in C. indicum; stamens twice as many as petals, inserted in the upper part of the calyx tube, exserted; style free except C. indicum, where it is adnate to the upper receptacle

Morphology Reproductive morphology Fruits

Fruit winged, ridged or angled.

Ecology

Found in low altitude habitats, often riverine or coastal.

Recognition

The stamens are usually the most conspicuous part of the inflorescence. The species with papery winged fruits are easily recognised as Combretum (and are distinguished from Malpighiaceae by their inferior ovary) and those without wings can be distinguished from Terminalia being easy to cut into, whereas Terminalia fruits are very resistant.

Combretaceae, G. E. Wickens. Flora of Tropical East Africa. 1973

Morphology General Habit

Trees, shrubs, shrublets or woody climbers, very rarely subherbaceous; scales or microscopic (and sometimes macroscopic) stalked glands present

Morphology Leaves

Leaves opposite, verticillate or rarely alternate, usually petiolate, almost always entire; petiole sometimes persisting (especially in climbers), forming a ± hooked spine

Morphology Reproductive morphology Flowers

Flowers hermaphrodite (in Flora area), regular or slightly zygomorphic (not in Flora area), 4–5-merous, in elongated or subcapitate axillary or extra-axillary spikes or racemes or in terminal or terminal and axillary, often leafy, panicles

Morphology Reproductive morphology Flowers Receptacle

Receptacle usually clearly divided into a lower part (lower receptacle) surrounding and adnate to the ovary, and an upper part (upper receptacle) varying from patelliform to infundibuliform and itself sometimes visibly differentiated into a lower part containing the disk (when present) and an often more expanded upper part

Morphology Reproductive morphology Flowers Calyx

Sepals 4 or 5 (rarely more), deltate to ± subulate or filiform, sometimes scarcely developed

Morphology Reproductive morphology Flowers Corolla

Petals usually 4 or 5 in Flora area (rarely absent in aberrant specimens), small and inconspicuous or showy and exceeding the sepals

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens twice as many as the petals, inserted in 1 or 2 series inside the upper receptacle and usually exserted

Morphology Reproductive morphology Flowers Disc

Disk glabrous or hairy, with or without a free margin, sometimes inconspicuous or absent

Morphology Reproductive morphology Flowers Gynoecium Pistil

Style free (in E. African species); stigma sometimes ± expanded; ovary completely inferior

Morphology Reproductive morphology Fruits

Fruit 4–5-winged, -ridged or -angled, sessile or stipitate, indehiscent or rarely tardily dehiscent; pericarp usuallythin and papery, sometimes leathery, more rarely fleshy

Morphology Reproductive morphology Seeds

Cotyledons various.

Combretaceae, A. W. Exell. Flora Zambesiaca 4. 1978

Morphology General Habit

Trees, shrubs, shrublets or woody climbers, very rarely subherbaceous. Plants lepidote or with microscopic (and sometimes macroscopic) stalked glands.

Morphology Leaves

Leaves opposite, verticillate or rarely alternate, usually petiolate (rarely subsessile), almost always entire; petiole sometimes persisting (especially in climbers) forming a ± hooked spine.

Morphology Reproductive morphology Flowers

Flowers always hermaphrodite (in our area), actinomorphic or slightly zygomorphic (not in our area), 4–5-merous, in elongated or subcapitate axillary or extra-axillary spikes or racemes or in terminal or terminal and axillary often leafy panicles.

Morphology Reproductive morphology Flowers Receptacle

Receptacle usually clearly divided into a lower part (lower receptacle) surrounding and adnate to the ovary and an upper part (upper receptacle) varying from patelliform to infundibuliform and itself sometimes visibly differentiated into a lower part containing the disk (when present) and an often more expanded upper part.

Morphology Reproductive morphology Flowers Calyx

Sepals (calyx-lobes) 4–5 (rarely more), deltate to ± subulate or filiform, sometimes scarcely developed.

Morphology Reproductive morphology Flowers Corolla

Petals usually 4–5 (rarely absent, in aberrant specimens and up to 7 in occasional flowers), small and inconspicuous to showy and exceeding the sepals, of various colours.

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens twice as many as the petals inserted in 1 or more usually 2 series inside the upper receptacle and usually exserted.

Morphology Reproductive morphology Flowers Disc

Disk glabrous or hairy, with or without a free margin, sometimes inconspicuous or absent.

Morphology Reproductive morphology Flowers Gynoecium Pistil

Style free (in our species); stigma sometimes ± expanded.

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary completely inferior.

Morphology Reproductive morphology Fruits

Fruit 4–5-winged, -ridged or -angled, sessile or stipitate, indehiscent or rarely tardily dehiscent; pericarp usually thin and papery, sometimes leathery, more rarely fleshy.

Morphology Reproductive morphology Seeds

Cotyledons various.

Combretaceae, A. W. Exell. Flora Zambesiaca 4. 1978

Morphology General Indumentum

Scales c. 40–80µ in diam., circular in outline, slightly convexly scalloped at each marginal cell; cells delimited by 8–10 radial walls alone; cell-walls clear; cells transparent.

Morphology General Habit

Shrubs or more rarely small trees.

Morphology Leaves

Leaves opposite, petiolate, lepidote.

Morphology Reproductive morphology Inflorescences

Inflorescences of terminal and axillary panicles.

Morphology Reproductive morphology Flowers

Flowers small, 4-merous, sessile.

Morphology Reproductive morphology Flowers Corolla

Petals 4, inserted near the margin of the disk.

Morphology Reproductive morphology Flowers Calyx

Calyx-tube shallowly campanulate, slightly oblique.

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 4, 1-seriate, antipetalous, not exserted.

Morphology Reproductive morphology Flowers Gynoecium Style

Style scarcely exserted.

Morphology Reproductive morphology Flowers Disc

Disk with pubescent scarcely free margin.

Morphology Reproductive morphology Flowers Gynoecium Ovary Ovules

Ovules 2.

Morphology Reproductive morphology Fruits

Fruit 4-winged.

Morphology Reproductive morphology Seeds

Cotyledons 2, unfolding spirally and arising above soil level (known only in M. tetrandrus).

Combretaceae, G. E. Wickens. Flora of Tropical East Africa. 1973

Morphology General Habit

Woody climbers; stalked glands present, peltate scales absent

Morphology Leaves

Leaves opposite or subopposite, entire, glabrous or hairy; bases of the petioles persisting as spines after leaf-fall

Morphology Reproductive morphology Flowers

Flowers hermaphrodite, regular or slightly zygomorphic, 5-merous, in elongated, usually unbranched, terminal or axillary bracteate spikes

Morphology Reproductive morphology Flowers Receptacle

Receptacle hairy or nearly glabrous; upper receptacle infundibuli-form, elongate-infundibuliform or trumpet-shaped

Morphology Reproductive morphology Flowers Calyx

Sepals triangular, sometimes with filiform tips

Morphology Reproductive morphology Flowers Corolla

Petals 2–20 mm. long, exceeding the sepals and enlarging during anthesis

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 10, biseriate, inserted near the mouth of the upper receptacle and not exserted beyond the petals

Morphology Reproductive morphology Flowers Disc

Disk narrowly tubular or absent

Morphology Reproductive morphology Flowers Gynoecium Style

Style adnate for part of its length to the inner wall of the upper receptacle

Morphology Reproductive morphology Fruits

Fruit 5-winged, dehiscent or indehiscent.