Deguelia rufescens urucu
The nomenclature of this species is rather confusing, with some botanists recognising the name we have used here, whilst all three alternative names given in the synonyms list are also recognised by different botanists.
There has been considerable confusion amongst botanists over the status of the genus Deguelia, with it variously being included in Derris and Lonchocarpus. We are following the treatment in Camargo & A.M.G. Azevedo Tozzi. 2014. A synopsis of the genus Deguelia (Leguminosae, Papilionoideae, Millettieae) in Brazil. Brittonia 66(1): 12-32, which treats it as distinct[
Derris urucu (Killip & A.C.Sm.) J.F.Macbr.
Lonchocarpus nicou urucu (Killip & A.C.Sm.) F.J.Herm.
Lonchocarpus urucu Killip & A.C.Sm.
Common Name: Barbasco
Deguelia rufescens urucu is an erect, evergreen shrub or a climbing plant producing several woody stems from its base that clamber into other plants for support.
This plant is an important source of the organic insecticide rotenone (the active ingredient in derris). It was first cultivated in S. America by the native people before the arrival of the Europeans, who used it as a fish poison and to kill ants. It is now cultivated on a fairly large scale in parts of tropical S. America and some other tropical areas, the rotenone being exported to various other countries throughout the world[
The plant contains rotenone and has been used traditionally as a fish poison[
] - the rotenone kills or stuns the fish making them easy to catch, but the fish remain perfectly edible for mammals. 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 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.
Northern S. America - Brazil, Colombia, Venezuela.
From grasslands to dense forests, from 'terra firme' to permanently inundated areas; at elevations around 100 - 120 metres[
|Other Uses Rating||
|Cultivation Status||Cultivated, Wild
Babasco is a plant of the moist tropics where it is found at elevations from near sea level to 1,340 metres[
]. It grows best in areas where the mean annual temperature ranges from 23 - 32°c, but can tolerate 15 - 41°c[
]. It prefers a mean annual rainfall in the range 2,300 - 2,700mm, but tolerates 2,000 - 3,100mm, and is found in areas with all year round rainfall and also where there is a distinct dry season[
Succeeds in full sun and in dappled shade[
]. Young plants benefit from some shade, while older plants make more vigorous growth in full light[
]. Grows best in a medium soil that is rich in organic matter, but also succeeds in heavier soils[
]. Prefers a pH in the range 5.5 - 6.5, but can tolerate 5 - 7[
The first harvest of the stems can be made when the plants are 2 - 3 years old from cuttings[
The roots are usually harvested during the dry season[
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[
The root is an important source of rotenone, widely used as an organic insecticide[
]. The rotenone content of the roots (ranging from 4 - 11%) is less than that of the related Lonchocarpus nicou (which ranges from 5 - 15%, with some clones yielding 20%). This, however, is somewhat balanced by the fact that the overall yield of roots is higher for this species[
If you have any useful information about this plant, please leave a comment. Comments have to be approved before they are shown here.