Senegalia Raf.

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

Distribution

A pantropical group of about 190 species with two species in New Guinea: Senegalia pluriglandulosa (Verdc.) Maslin, Seigler & Ebinger is a prickly climber, and S. rugata (Lam.) Britton & Rose, a tree species treated as Acacia concinna (Willd.) DC. in Verdcourt (1979), but see Maslin et al. (2013) for the discussion of the most appropriate name to use.

Morphology General Habit

Trees, shrubs, scramblers and lianas, S. rugata recorded to 18 m, not spiny, but prickles present on internodes. Stipules narrowly triangular, caducous

Morphology Leaves

Leaves bipinnate, glands present between the apical 2 pairs of pinnae, leaflets opposite, sensitive to the touch

Morphology Reproductive morphology Inflorescences

Inflorescences of sessile flowers in heads, forming extensive terminal or axillary panicles

Morphology Reproductive morphology Flowers

Flower buds purple or dark red; corolla cream or white; ovary stipitate, with a tubular nectary below

Morphology Reproductive morphology Fruits

Fruit flat, often with sinuous margins, dehiscing into 2 valves or rarely falling apart in one-seeded segments

Morphology Reproductive morphology Seeds

Seeds elliptic to orbicular, slightly flattened, with pleurogram.

Ecology

Senegalia rugata is found in rain forest and disturbed habitats to 1050 m, and is probably introduced to eastern Malesia (the type being from India).

Recognition

The species can be recognised by the bipinnate leaves (not flattened and simple leaf-like structures, the phyllodes of Acacia sensu stricto), inflorescences sometimes elongated terminal or axillary panicles, flower buds purple or dark red but with the mature corollas being cream or white with white stamens, and the fruit flattened, with c. 7 seeds. The leaflets are sensitive but not nearly so pronounced as in some Mimosa species.