Germination of Witchweed ( Striga lutea Lour.): Isolation and Properties of a Potent Stimulant

A crystalline germination stimulant (trivial name strigol) for the root parasite, witchweed ( Striga lutea Lour.), has been isolated from cotton root exudates and characterized as a C 19 H 22 O 6 compound. Although apparently different from known plant hormones, the stimulant is active at hormonal levels, causing germination at concentrations less than 10 -5 part per million.