Pterocarpus Angolensis

PTEROCARPUS ANGOLENSIS also known as “Pterocarpusbussei, Pterocarpus dekindtianus”


      Family: Fabaceae or Leguminosae  (Pea, bean or legume family).  After the Orchidaceae and the Asteraceae, the Fabaceae is the third largest Angiosperm (flowering plants) family with 700+ genera and close to 20 000 species.  Local Tree genera on this website include Acacia  (Vauchellia,Senegalia), Albizia,BauhiniaBolusanthus, Burkea, Calpurnia, Colophospermum, Cordyla, Cyclopia, Dichrostachys, ErythrinaErythrophleum, Faidherbia, Indigofera, Mundulea, Peltophorum, Philenoptera, Piliostigma, Schotia and Xanthocercis. The Fabaceae are recognizable by their fruit and by their pinnately compound Leaves. Leaves may also be simple – even bilobed and usually have stipules – some of which may be spinescent.  Leaflets are usually entire.  Flowers are bisexual and bracteate.  Regular flowers usually have 4-5 sepals and the same number of petals.  Irregular flowers have 4-5 sepals and 5 or less petals.  Stamens have anthers that have 2 pollen sacs and there are usually at least twice the number of stamens as petals – often 10.  The superior Ovary has one locule that may contain 1 or more ovules.  The Stigma and Style are simple.  The single carpel develops into the Fruit, which is usually a pod.  This pod dehisces on both sides and may break into segments.


Tree, Fruit and Leaves


     In South Africa, this Tree is usually up to 15m high.  Beyond our northern boarders, it may reach 30m or more in height e.g. in Mozambique.  The long straight, usually single Trunk is up to 0,6m wide and has a flat spreading crown – especially when on its own.  Lichen (composite organism arising from a mutualistic relationship between fungi or cyanobacteria and algae species) may be present on the trunk.  The darkish grey Bark is rough and longitudinal fissured with protruding parts that are almost rectangular .  Young branches are hairy.  Sap is sticky and blood red – hence the common name “bloodwood”.  Damaged bark leaks this color.


     The flattened, often wavy, indehiscent Fruit is an orbicular (circular or disc-shaped) Pod with a membranous coffee-colored wing up to 15cm (usually less) across.  A persistent Calyx is visible below the pod .  There is a centrally situated, clearly visible thickened seed case, which is setose (covered with long bristles).  This “circular” pod, with its bristles, is distinctive – especially in winter.

     Each pod is initially green and may have up to 3 smooth, kidney shaped small Seeds.  It takes about 3 000 seeds to have a mass of 1kg.  The seeds lack endosperm (the starch and oil-containing tissue of many seeds; often referred to as albumen).  The shape of the fruit aids wind dispersal – usually up to about 50m from the tree.  This distance is mainly dependent on the wind and the height of the tree (Jan-Oct).  The fruit hangs on the tree and may even remain there through winter


      The yellow, sweetly scented, sweet pea like Flowers appear shortly before the leaves and flowering lasts about 3 weeks.  They have narrow hairy Bracts (modified leaves associated with reproductive structures).  Flowers are bisexual, and zygomorphic (irregular floral parts are unequal in size or form so that the flower is capable of division into essentially symmetrical halves by only one longitudinal plane passing through the axis).  The flowers develop in hanging Racemes (a simple elongated inflorescence with stalked flowers that open in succession towards the apex).  These are up to 12cm long.  The hairy Pedicel (stalk of a single flower) is up to 2cm long.  The 5-short lobed hairy Calyx is campanulate (bell shaped) with the upper 2 lobes partially joined.  The Corolla has 5 crinkled Petals which consists of the single large uppermost Vexillum or standard petal, two expanded Wing petals and 2 fused Keel petals at the base.  10 connate (united) Stamens are present – one of which may be free or partly so.  Stamens are longer than the petals.  The dorsifixed Anthers are equal in length and dehisce longitudinally.  There is a single Pistil (a unit of the Gynoecium, the female element of the flower, composed of the Ovary, Style and Stigma) with a superior Ovary and a small Stigm

Distribution & Ecology

     These Trees occur naturally on well-drained rocky Savanna (rolling grassland scattered with shrubs and isolated trees, which can be found between a tropical rain forest and desert biome) and the hillsides below 1 600m.  They are often located in deep sandy soils, where the rainfall is greater than 500mm per year.  The tree is frost sensitive and has a poor capacity for Coppicing  (when stems are cut or burned it causes regrowth from the stump or roots).  Leaves are relatively spares on the tree.  This allow sun to penetrate close to the trunk and permits grass to become well established below it.  The Bark of saplings is fire resistant.  Geographical location: Northern KwaZulu-Natal e.g. Lebombo mountains, Mpumalanga, Limpopo, Swaziland, Mozambique, Namibia e.g. Caprivi Strip, Zimbabwe Zambia, and Northwards into Tropical Africa.  Baboons, monkeys and yellow-footed Squirrels (Paraxerus cepapi) eat the Pods.  These squirrels are small (about 200g) and are widespread in southern Africa.  Kudu and elephant browse the Leaves.  Butterfly larvae of the Emperor or Bush Charaxes: (Charaxes achaemenes) also feed on the leaves.  Flowers attract bees and make this a good honey tree.  Monkeys, baboons and yellow-footed squirrels (Paraxerus cepapi) consume the flowers.  This is a protected tree in the South Africa.


     These attractive Trees are sensitive to frost.  The Wood is similar to that is Albizia versicolor and has a relatively low density – about 500kg per cubic meter.  It is one of the most widely used timber trees and is considered second only to stinkwood for making furniture.  The sawdust may be irritant.  Sapwood is pale grey to yellow and may be susceptible to borer attack.  The Heartwood is light brown to dark reddish brown with wavy streaks.  It is strong, durable, attractive and is also used for canoe building and carving as well as for parquet flooring, construction, doors, windows, and fuel.  The wood works and turns well and only shrinks slightly when drying.  Wood to the north of South Africa is usually lighter.  Root heartwood yields a brownish dye.  Extracts from the roots kill parasitic flatworms, which may carry bilharzia.  The fibrous Inner bark is used in basket manufacture.  The red Sap is used for dye.  It is also used in local medicine.  Root bark is powdered, mixed with fat and used to colour skin.  The Seeds are difficult to germinate, however filed seeds are slightly more successful.  Usually only 1% of seeds germinate and last more than 1 year.  Heat e.g. from a fire may speed up the germination.  Truncheons (stem cutting from a selected plant – used to produce genetically identically new plants) should be planted in spring when the sap is rising.

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