2017 ASHS Annual Conference

The golden shower tree, Cassia fistula (L.), is a traffic stopper when in bloom with golden yellow three-inch flowers that hang in clusters 30 to 45 cm in length. However, the copious production of messy and sometimes hazardous fruits and seeds make the normal diploid form of this species high maintenance and potentially invasive. A sterile form of this prolific seed producing tree would be highly desirable for tropical landscapes. Triploid plants are usually sterile, and can usually be produced by crossing tetraploid and diploid plants of the same species. In a first step toward creating triploid C. fistula plants, tetraploid and mixoploid individuals were induced from colchicine treatments on recently germinated seedlings. Upon flowering, three 5-year old autotetraploid and one mixoploid C. fistula plants were completely sterile, and remained sterile in three subsequent years of flowering. It is not uncommon for autotetraploid plants to have reduced fertility, but complete sterility was unexpected. The sterile autotetraploid plants are being vegetatively propagated for introduction to the Hawaii landscape industry.