1992 Volume 36 Issue 1 Pages 28-36
In the inflorescence of castor-oil plants, the dichasia developed as a spiral on the inflorescence axis, with the male dichasia developing in the lower part of the axis and the female ones in the upper part, while in the boundary part, mixed dichasia developed. Within a dichasium, the higher the order of the flower was, the later the flower bloom occurred. The male flowers started to bloom a little later than the female flowers. Blooming proceeded from the flowers in the lower position to those in the upper position on the inflorescence axis when flowers of the same order were observed. The female flowers bloomed in the same way as the male flowers with one exception. In the case of the female flowers, only one flower developed in the uppermost dichasium on the inflorescence axis, and the flower bloomed as early as the flowers of the lowest female dichasium. Although the flowering time of the flowers at every position hardly changed by the pinching of lateral buds on the first flowering day, the high order flowers in the dichasia, which did not bloom in the control plant, started to bloom and the flowering period of the inflorescence was prolonged by the pinching of lateral buds. The female flowers which bloomed later frequently gave rise to immature fruits at harvest time. The flowering period of an inflorescence was about 10 days in the control plants, and the period seemed to be important for the determination of the number of fruits per dichasium on the inflorescence axis. Also the number of dichasia on the inflorescence axis increased and the male flowers started to bloom earlier in the late-season culture.
