不孕花 Sterile flower
不孕花指種子植物中的雌蕊和雄蕊完全退化消失，或由於發育不完全，不能結出種子的花。在香港，洋紫荊為不育樹，其花不能生產種子，所以所有洋紫荊都是由同一棵洋紫荊母樹以無性繁殖方法（如嫁接法）產生的後代。
Sterile flower is flower that cannot produce seeds because stamens and pistils of seed plants are completely degenerated or underdeveloped. In Hong Kong, Bauhinia x blakeana is a sterile tree whose flowers cannot produce seeds, so all Bauhinia x blakeana are offsprings from the same mother tree by asexual reproduction methods, such as grafting.
