[6][13] The wood is spongy and extremely lightweight, it is often mistakenly called pith, this acts to help the plant stay afloat.

Their branches touching the soil or water surface, or submerged underwater, are densely covered in adventitious roots.

Isolated vessels are scattered in this mass of tracheids, accompanied by tangentially arranged groups of libriform cells (uncommon, resembling phloem, but very slender and relatively thick-walled).

Their petiole and rhachis together measure 4–16cm long, and both are densely covered with both stiff bristly hairs and shorter pubescence, and also often with short, minute spinelets.

[6] These stipules have a lobe on one side only, are velvety in texture, broadly ovate in shape with the upper portion deltoid-ovate and ending in an acute tip, are (7-)10–13mm in length, (3-)5-6(-9)mm in width, and eventually fall off as the leaf matures.

The leaflets are (5-)8–26.5(-30)mm long and 4–10mm wide, entire, mucronulate, their shape is elliptic and oblong or obovate, with their apex truncate, retuse or slightly emarginate, and their bases where they connect to the rhachis are obliquely rounded (not a mirror image).

[6][10][11] The 30—45mm long,[6] relatively large,[14] beautiful flowers[18] are single or usually bunched together in groups of two to four in an axillary, racemous inflorescences.

[10][11] The seeds are contained in flattened, erect pods that grow in contorted into twisted full or half spirals on the tree.

These brachyrhizae all look very similar to each other, they do not branch or elongate further, but grow a special bark containing corky inner tangential cell walls.

They have no genuine root hairs above the zone of their elongation, and very rarely branch, unless the growing tip hits the soil or is damaged.

Unlike mangroves and other swamp trees such as Taxodium distichum, this species does not make specialised pneumatophores, required for gas exchange in the anoxic swamp mud -instead, this species relies upon the adventitious roots which are exposed with drops in water level, and richly sprout from the lower part of the bole above the water level.

[12] Pollen grains are monads, polar axis = (24.0) 27.9 ± 0.4 (30.6) μm x equatorial axis = (26.0) 29.3 ± 0.4 (31.5) μm, oblate spheroial to prolate spheroidal, circular outline in equatorial view; 3-colporate, colpus very long, operculum areolate, membrane psilate, margo psilate-perfurate; endoaperture circular, lalongate to lolongate, sexine heterobrochate, microrreticulate to reticulate, muri straigth, continuoos, lumina polygonal, sexine de 1.6 a 2.7 times ticker than nexine.

elaphroxylon is easily recognised among similar aquatic species by being conspicuously thorny, as opposed to glabrous or only hispid, and having strongly curved or contorted bean pods.

[6] The holotype, which is kept in Paris, was collected by George Samuel Perrottet in northwestern Senegal on a small island in the lake of "N'Gher, or Panié-Foul" at the mouth of the "Marigot de Taoué River".

[10][11][20] It was first described as Herminiera elaphroxylon by Perrottet and Jean Baptiste Antoine Guillemin in 1830–1833, who mention that the natives knew the plant by the name bilor or billeur, and that Michel Adanson had already written about it under that name growing on a floating island in his book about his time in Senegal, Voyage au Sénégal.

[20] It was moved to the subgenus Ochopodium in the genus Aeschynomene by Paul Hermann Wilhelm Taubert in 1894 in the book series Die Natürlichen Pflanzenfamilien.

[18] Smithia grandidieri, collected by Alfred Grandidier on the southwest coast of Madagascar and thence described in 1883, was synonymised with Aeschynomene elaphroxylon in 1971.

[3] In Mangochi District in southern Malawi, it is found growing along the lake shores and in seasonally flooded areas associated with the shrubs Aeschynomene afraspera, Ae.

cristata, Sesbania sesban, S. sericea and S. rostrata, and the grasses Eriochloa borumensis, Panicum repens, Phragmites mauritianus and Vossia cuspidata.

The ambatch tree is associated with the fern Cyclosorus striatus here, as well as the grasses Leersia hexandra and African wild rice Oryza barthii, the curcubit vine Zehneria capilacea and the herbs Ipomoea aquatica, Pentodon pentandrus and Polygonum tomentosum.

elaphroxylon and Sesbania sesban, with Euphorbia tirucalli and Acacia tortilis as co-dominant species, and characterised by the presence of Withania somnifera.

The sap-sucking shield bug Brachyplatys testudonigro, which is common in Malawi, likely does feed upon it, as it has regularly found on other Aeschynomene and many other similar legumes like Crotalaria, Indigofera and Tephrosia.

[31] In 1969 Czechoslovak botanists Jan Jeník and Jarmila Kubíková published their discovery of a new type of bacteroidal nodule which they had observed on the aboveground parts of the stems in Ghana.

A concentration of Gram positive pleomorphic rod-shaped bacteria very different than the symbiotic rhizobia normally living within legumes were found in these structures.

[20] The trunk wood is traditionally used to make floats for fishing nets, and used in raft, canoe[1][11][12] and boat construction, for example around Lake Chad.

[20] On the remote Lake Keilack in South Kordofan, much visited by nomads with their cattle, three bundles of trunks are bound together to make a small rafts propelled using a long pole like a punt.

[38] It is sometimes seen as a nuisance in Lake Chad, as the rapidly growing stands are so very densely matted with interlocking roots, they can make it very difficult to fish.

elaphroxylon is locally called bofoffe by the Zay people who live on islands as well as shore areas of Lake Ziway in the Ethiopian Rift Valley.

elaphroxylon of Lake Ziway was found to bioaccumulate a high concentration of the trace element manganese (1.6 × 103mg per kg of dry weight).

[32] Based on the description as related by Schweinfurth, it would appear that the plants in cultivation, in Egypt at least, grew differently than those in the wild, as the plants lacked the aerial roots described by earlier writers and seen by him elsewhere in Africa, although we can assume that Schweinfurth observed the brachyrhizae, from his description of "filzartiges Geflecht" of roots.