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
Barbasco 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). The plant was first cultivated in S. America by the native people before the arrival of the Europeans. They 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, the rotenone being exported to various other countries throughout the world[
The plant is used as a fish poison[
Northern S. America - Brazil, Colombia, Venezuela.
|Other Uses Rating||
|Cultivation Status||Cultivated, Wild
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[
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