A single foliar spray of a morphactin (n-butyl-9-hydroxyfluorene-(9)-carboxylate) was applied at a concentration of 1, 10, 100, or 1000 ppm to 6-week-old plants of ribbed gourd (Luffa acutangula Roxb.), a monoecious cultivar, Pusa Nasdar. Growth of the main axis was only stimulated at 1 ppm and was increasingly inhibited at higher concentrations. Morphactin weakened apical dominance and increased the number of lateral branches. The production of pistillate and staminate flowers was increased and then decreased by morphactin, up to a concentration of 100 ppm. At the same concentrations it also increased femaleness, number of fruits, and therefore the yield. A drastic inhibition of total flowering, fruit-set, and therefore yield was recorded at 1000 ppm. Parthenocarpic fruits developed only at 100 and 1000 ppm.