Aeschynomene elaphroxylon

What to Eat

Edible parts: Seeds

The seeds are eaten.

Where to Find It

It is a tropical plant. It grows in lakes and swamps. It is usually in water 1-2 m deep. It grows in east Africa from 500-1,000 m altitude.

Africa, Angola, Central Africa, Chad, Congo, East Africa, Egypt, Ethiopia, Ghana, Indonesia, Madagascar, Malawi, Mozambique, Nigeria, North Africa, SE Asia, Senegal, Southern Africa, South America, Sudan, West Africa, Zambia, Zimbabwe,

How to Identify

A shrub or small tree. It grows about 9 m tall. The stem is swollen and almost cone shaped. It has sticky hairs. The stem is soft. The leaves have 20-40 side leaflets and these are 1-3 cm long by 1 cm wide. They are oblong but flattened at the top and rounded at the base. There are some hairs underneath. There are 1-4 flowers on a stalk 1.3 cm long. The flowers are large and orange-yellow. The fruit are twisted pods. They are 10-14 cm long. They have lumpy hairs. The seeds are dark purple-brown. They are kidney shaped and 6 mm long by 4 mm wide and 2 mm thick.

How to Grow

The plant is well suited to seasonally flooded localities where the soil remains wet. The lower part of the stem of plants in the wild is often submerged. The plant is capable of rapidly colonizing rivers and swamps. The stems and branches may form dense floating masses that clog watercourses. The plant is sometimes grown as an ornamental for the beauty of its conspicuous orange-yellow flowers, especially along the sides of water where it also serves to prevent erosion This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby.

Other Uses

The pale coloured and spongy wood is very light. Known as ambatch wood, it weighs around 110 - 190 kilos per cubic metre and is one of the lightest known woods. It is used for making canoes, rafts and shields, and also for building poles and furniture. The stems are used for fishing-net floats and sandals. The wood is attached to spears to serve as a buoy. This species could be a good substitute for the wood of balsa (Ochroma pyramidale) for special applications such as model making. The plant deserves more attention as a nitrogen fixing tree that is potentially useful for enhancing soil fertility in temporarily flooded agricultural land, e.g. as a green manure in rice cultivation. It is grown along watersides both as an ornamental, for the beauty of its flowers, and also to prevent erosion. When grown in wet areas it produces a massive root system with adventitious roots on the lower bole above the water level and also on prostrate stems and submerged parts. These become a barrier to floating vegetative flotsam, resulting in an accumulation of vegetative matter which settles and fills inundated areas.

Aeschynomene elaphroxylon, also known as an ambatch, pith-tree, balsa wood tree, or umburu, is a common large shrub to small tree in the genus Aeschynomene in the family Fabaceae, growing in swamps, lakes and rivers in Tropical Africa. This is an unusual leguminous tree in that it grows in water as a freshwater mangrove, with an extremely lightweight wood acting as a float and a specialised root system sprouting from the trunk which forms a tangled web hanging through the water and sprawling through the mud. It has adventitious roots and roots which are differentiated into special structures adapted to the swamp environment. It can even grow as floating islands of drifting forests. The name 'ambatch' derives from the name of the plant in the Arabic dialect spoken in Nigeria known as Shuwa by the British. It is called Nile pith tree in Sri Lanka, ambach there and in Malaysia, or ambatsch in Malaysia. The extremely light, spongy, but rot-resistant wood is traditionally used to make floats for fishing nets and the trunks are lashed together to make rafts, as well as more sophisticated items.

Production

It grows very quickly.

Notes

There are 150 Aeschynomene species.

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