Common Name: Ambila

General Information

Pterocarpus angolensis is a medium sized deciduous tree with an open, rounded or spreading crown; it usually grows from 5 - 20 metres tall but specimens up to 35 metres are recorded[, , ]. Occasionally the plant is no more than a shrub up to 5 metres tall[]. Trees growing on good sites in full light live for up to 100 years, by which age they are about 20 metres or more tall, with a crown diameter of 10 - 12 metres and a bole diameter of 50 - 60 cm[].
A key timber species throughout its range, yielding a high quality wood. Large stands are known to still occur in places, particularly in protected areas in South Africa, Botswana and Namibia[]. Regeneration is sufficient but may be episodic, depending on fire or high rainfall[]. The plant is also often grown as an ornamental street and shade tree, being valued especially for its masses of fragrant orange-yellow flowers[, ].
In most regions through its range, the species has become less frequent, especially where it is heavily used by local populations[]. Across parts of its range the largest and most mature trees are at risk from over exploitation for timber, causing decline in some subpopulations outside of protected areas and sometimes inside protected sites due to both legal and illegal logging activity. In areas of extraction the size structure of subpopulations has become truncated, with smaller trees being much more common than those of larger size, which reduces the amount of seed being produced by the population. There is concern over the impact this might have on regeneration at some sites. Further investigation is needed to establish the extent to which this threatens the future viability of the species. Despite these threats to the species a large population of Pterocarpus angolensis is likely to remain across its range as not all trees are exploitable due to defects or being small in size. The species also has a large extent of occurrence. The persistence of the species in a suffrutex stage and its ability to colonise exposed landscapes are also to its benefit. The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2018)[].

Known Hazards

The bark has been used as fish poison[].
The dry sawdust may cause irritation to nose and bronchia[].

Botanical References

Range

Africa - Tanzania to Angola, south to S. Africa.

Habitat

Found in all types of woodland and wooded savannah[]. Typically found in so-called miombo woodland with Brachystegia and other deciduous trees, in wooded grassland and savannah, at elevations from sea-level up to 1,650 metres[].

Properties

Conservation Status	Least Concern
Medicinal Rating
Other Uses Rating
Habit	Deciduous Tree
Height	25.00 m
Growth Rate	Fast
Pollinators	Bees
Cultivation Status	Ornamental, Wild

Cultivation Details

Ambali is a tree of low to medium elevations in the tropics, where it can be found from sea level to around 1,650 metres[]. It grows best in areas where annual daytime temperatures are within the range 15 - 32°c, but can tolerate 12 - 38°c[]. It is not resistant to frost, although older trees survive very light frosts[]. The plant can survive temperatures down to about -1°c[]. It prefers a climate with well-defined wet and dry seasons, with a mean annual rainfall in the range 700 - 1,500mm, but tolerates 500 - 2,000mm[].
Requires a sunny position, even when young[]. Requires a well-drained, medium to light soil of low to moderate fertility[]. Tolerates moderate levels of salt in the soil[]. Prefers a pH in the range 5.5 - 7, tolerating 5 - 7.5[].
Trees do not coppice well, if at all[].
Growth is slow and variable for at least the first seven years, making it less suitable for growing in plantations[].
After germination the seedling rapidly develops several shoots and a strong taproot, which may reach to a depth of 1 metre in the first year[]. The shoots reach about 15 cm length in the first year and often die back in the dry season[]. The plants enter a suffrutex stage, in which the root expands in size and lateral roots develop in the top 50 cm of the soil, while shoots usually die back to below ground level in the dry season[]. New shoots develop in the rainy season. This stage may last for 10 years (sometimes up to 25 years) until the root has sufficiently developed to allow the above-ground part of the sapling to survive the dry season[].
After the suffrutex stage, the growth is fast, up to 2 metres or more in one year, and the tree rapidly reaches a height where it cannot be reached by most browsing animals[].
Compared to other trees the saplings with a thick corky bark are extremely fire resistant, sometimes surviving temperatures of up to 450°c, and fires contribute to pruning side branches and multiple stems[].
Trees start flowering when they have a permanent stem of 15 - 20 years old, but full development of fruits usually only starts when trees are about 35 years old[].
This species is one of several that supply a red resin from their stem. This resin, often known as 'Dragon's Blood' is often used as an external application to treat a range of skin problems and injuries[]. Dragon's Blood can be obtained from several species in this genus, as well as from three other distinct genera - Dracaena species, Croton species and Daemonorops species[]
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

The bark, with its blood-red, gummy, resinous exudate, (‘false dragon’s blood’ or ‘kino’) is often used in traditional medicine. In particular, it is a powerful astringent, being used in the treatment of conditions such as diarrhoea, heavy menstruation, nose bleeding, headache, stomach-ache, blood in the urine and schistosomiasis[, ].
Applied externally, the bark is used in the treatment of sores, skin problems, mouth ulcers, 303 etc[]. It is heated in water and mixed with figs then massaged on the breast to stimulate lactation[]. A cold infusion from the bark alone provides a remedy for nettle rash.[].

A decoction of the root is believed to cure malaria, blackwater fever and gonorrhoea[, ]. An infusion made from the roots is taken orally for the treatment of diarrhoea, bilharzia and abdominal pains[]. Roots are burnt and the ashes drunk in water to treat asthma and tuberculosis[].
Corneal ulcers are bathed in an eyewash obtained when roots of the tree are first cleaned and then left to soak in water for 6 hours. In the follow-up treatment of this ailment, flowers are placed in boiling water over which the patient holds the face, allowing the steam to fill the eyes[]

Ripe seeds are burnt and the ashes applied as a dressing on wounds, inflammation, psoriasis and bleeding gums[, ].

The sap is reputed to heal sores, including ringworm sores and stab wounds, and to treat various other ailments[] Dropping sap into the eyes is used to treat cataracts and sore eyes[].

Root extracts are lethal to adult schistosomes causing bilharzia and are comparable to praziquantel, an efficacious antischistosomal drug[].

Agroforestry Uses:

A nitrogen fixing plant, it has been used for soil conservation, dune fixation, live fencing and as an ornamental casting a light shade and with attractive fruits[, ].
The tree is regarded as an indicator of well-drained soils[, ].

Other Uses

The heartwood of the roots, pounded to powder, yields a fast brownish red dye which is used mainly to dye palm-leaf fibres for basket weaving[]. Strips of palm leaves are boiled for about 12 hours in a dye bath containing hot water and the bark. After drying, the resulting red-brown fibres are used to obtain coloured designs in basketry weaving[]. The dye obtained by extracting finely chopped roots or wood in alcohol can be used to dye wool and cotton various shades of brown to bright red[].
The powder is also mixed with oil or fat to make a cosmetic pomade, which had great cultural importance[]. It is traditionally applied to all exposed portions of the body, including hair, face, breasts, arms and legs[]. It is also used to dye leather clothing, which is the traditional form of clothing for men and women alike and it still has cosmetic, medicinal and symbolic importance[].
The inner bark and heartwood of the trunk and branches are also said to be used by some people to obtain dye[].

The kino resin from the bark can be harvested by making incisions in the bark and collecting the exuding sap[]. The sap contains 77% tannins[, ], and is used as a long-lasting dye[].

The inner bark is fibrous and is used in basketry[].

The tree shows considerable promise as a firebreak[].

The heartwood is pale to dark brown or reddish brown, often with streaks; it is distinctly demarcated from the pale grey or pale yellow sapwood[]. The grain is straight to interlocked, texture medium to coarse[]. The wood is relatively light, it dries well but slowly, without warping and with little or no tendency to check or split[]. Once dry, it is very stable[]. The wood works well with hand and machine tools, only moderately blunting cutters; straight-grained material planes and finishes well[, ]. The bending properties are moderate. The wood is easy to peel and slice, and has good gluing and excellent turning and carving properties[]. The heartwood is moderately durable; it is moderately resistant to termites and marine borers[]. The sapwood is liable to powder-post beetle attack. The heartwood is resistant to preservative treatment, the sapwood moderately resistant[]. A very valuable timber, it is a good substitute for Indian teak, which it somewhat resembles, although not so straight -grained. It is used for construction, carpentry, high class furniture manufacture (tables, chairs, benches), parquet flooring and veneer, and in South Africa and Namibia particularly for wood carving (bowls, spoons and walking sticks). Due to its flexibility, resistance and light weight it is also useful for boats, doors and windows[, , ].
The wood is occasionally used for firewood[].

Propagation

Seed - although trees can produce ample seed (up to 10,000 fruits/ha are recorded), germination is poor. Under natural conditions only 2% of the seed germinates and half of the seedlings produced die in the first year[].
Another report gives a totally different story - Seeds not extracted from the pod have a low germination possibly because of physical or mechanical dormancy exerted by the pericarp. The seed itself has only slight physical dormancy. Germination is improved by scarification but even without pre-treatment high germination can be expected[]. Seeds can be sown in seedbeds and seedlings transplanted into pots, or sown directly in pots. For testing, germination in sand is recommended. The species has both rhizobium and mycorrhizal associations. Inoculation is applicable where these microsymbionts are absent from the nursery soil or planting site[].
At moisture contents of 4 - 6%, seeds can be stored cold for at least 3 years[].
The trees can be grown from large cuttings[].

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