Development of male and female gametophytes in simple and double flowers of Hibiscus syriacus

The cytomorphological characteristics of microsporogenesis and macrosporogenesis in simple and double flowers of Hibiscus syriacus as well as the development of their male and female gametophytes were investigated.Resultsshowed that the microsporic tetrads of the simple flower belong to the tetrahedral type and mature pollen is two-celled with bristles on the surface. The development of gynoecia lags about one week behind that of androecia. As mononuclear microspores form, the megaspore mother cells enter the stage of miosis. The embryo sac belongs to the polygonum type. The pistils and stamens of double flowers of H. syriacus all develop into petals and abort. Double fertilization is observed in the simple flower four days after blossom and the mature embryo forms after stages of globular, heart-shaped, torpedo-shaped and cotyledon embryos. The endosperm belongs to the nuclear type and mature seeds bear no endosperm.