Common Name:

General Information

Millettia laurentii is a tree with spreading, drooping branches; it usually grows up to 30 metres tall but exceptional trees can reach 50 metres. The cylindrical bole is often slightly bent; it can be free of branches for up to 20 metres (though usually much less), up to 120cm in diameter and with small buttresses or fluted at base[].
The tree is very commonly harvested from the wild for its valuable timber. It is used locally and is also much exported. This is one of 33 species named as being a suitable Hongmu (red wood) timber, used for producing high quality Chinese furniture following traditions from the Ming and Quing dynasty[]. The tree also has local medicinal uses and is sometimes used as a pioneer species when restoring native woodland. A very ornamental tree, it is sometimes grown along roads, in parks and gardens[, ]. Trees in full flower are very conspicuous, being covered by purplish blue flowers[].
A very widely exploited timber species, in much of its range it is threatened with over exploitation for its decorative timber. The plant is classified as 'Endangered' in the IUCN Red List of Threatened Species(1998)[].

Known Hazards

The bark is used as fish poison and arrow poison[].
Contact with the fine sawdust produced during processing may cause occupational asthma and allergic dermatitis in workers[]. A quinone (2,6-dimethoxy-1, 4-benzoquinone) has been isolated from the wood and identified as a contact allergen[].
Millettia species in general contain a range of toxic substances, especially isoflavones. Rotenone is probably the best known of these isoflavones and it is found especially in the seeds and roots of the plants. Rotenone is often used locally as a fish poison - the rotenone kills or stuns the fish making them easy to catch, but the fish remain perfectly safe for warm-blooded creatures to eat. Rotenone is classified by the World Health Organization as moderately hazardous. It is mildly toxic to humans and other mammals, but extremely toxic to many insects (hence its use as an insecticide) and also to aquatic life, including fish. This higher toxicity in fish and insects is because the lipophilic rotenone is easily taken up through the gills or trachea, but not as easily through the skin or the gastrointestinal tract. The lowest lethal dose for a child is 143 mg/kg, but human deaths from rotenone poisoning are rare because its irritating action causes vomiting. Deliberate ingestion of rotenone, however, can be fatal.
The compound decomposes when exposed to sunlight and usually has an activity of six days in the environment.
Millettia species often also contain other potentially toxic compounds, especially saponins and alkaloids[].

Botanical References

Range

West tropical Africa - Cameroon, Central African Republic, Equatorial Guinea, Gabon, Congo, DR Congo.

Habitat

Rainforest, often in well-drained localities, but also in forest subject to regular inundation; also in riverine forest and tree savannah[].

Properties

Conservation Status	Endangered
Medicinal Rating
Other Uses Rating
Habit	Tree
Height	25.00 m
Pollinators	Bees
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

Species in this genus generally grow best in a sunny position in a fertile, moisture-retentive but well-drained soil[].
The wood does not float and therefore cannot be transported by river[].
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[].

Edible Uses

None known

Medicinal

In traditional medicine a bark decoction is used to treat liver complaints, diabetes, hernia, skin diseases, constipation, fever and rheumatism. The bark is also applied as an expectorant, emetic and vermifuge, as well as to treat epilepsy, smallpox, oedema, sores and abscesses[].

Several isoflavones have been isolated from the heartwood, and several alkaloids, including guanidine alkaloids, from bark and seeds[].

Agroforestry Uses:

Flowering trees provide nectar to honey bees[].
Stem cuttings are planted as a live fence[].
The tree is used as a pioneer, being planted for the reforestation of formerly cultivated land[].

Other Uses

The bark has insecticidal properties[].

The seeds contain about 35% oil, though no uses are mentioned[].

The heartwood is yellow when freshly sawn but darkens on exposure to dark brown or black-brown, with black streaks; it is sharply demarcated from the 2 - 5cm wide band of pale yellow sapwood. The grain is straight, texture medium to coarse. The wood is heavy, hard, elastic and very durable, being resistant to fungal, dry-wood borer and termite attacks and moderately resistant to marine borers, but the sapwood is susceptible to attack by powder-post beetles. It has a tendency to split. It saws and works well, but force is required and sawteeth and cutting tools may blunt rapidly; stellite-tipped sawteeth and tungsten-carbide tipped cutting tools are recommended; it is difficult to polish and the use of a finishing wax is recommended; pre-boring before nailing and screwing is needed; it slices well and can also be rotary cut, but intensive steaming is then needed. The gluing and varnishing properties are poor due to the presence of resin cells, but the use of a filler improves the results considerably. The wood is commonly used for heavy flooring, interior and exterior joinery, interior and exterior panelling, cabinet work, furniture, carving, turnery and sliced veneer. It is also suitable for heavy construction, mine props, vehicle bodies, implements, sporting goods, toys, novelties, boxes, crates and railway sleepers. It is in high demand for decorative furniture and parquet flooring. It is also used for high-quality musical instruments, especially guitars; it is said to give a good and strong tone. It is popular for the production of sculptures, masks and drums[, ].

Propagation

Like many species within the family Fabaceae, once they have been dried for storage the seeds of this species may benefit from scarification before sowing in order to speed up and improve germination. This can usually be done by pouring a small amount of nearly boiling water on the seeds (being careful not to cook them!) and then soaking them for 12 - 24 hours in warm water. By this time they should have imbibed moisture and swollen - if they have not, then carefully make a nick in the seedcoat (being careful not to damage the embryo) and soak for a further 12 hours before sowing[].
Cuttings. In a trial in DR Congo, 48% of stem cuttings planted at the onset of the rainy season sprouted[].

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