Abstract:Early differentiation of floral primordium before the appearance of megascopic primordia protuberance was investigated im Cucumis sativus L. The results showed that the differentiation of floral primordium and flower firstly occurred at the axil of the fire leaf. Before the appearance of megascopic primordia protuberance, a spherical cell aggregate with active cell division appeared at subepidermis as an early primordium at 6-7 day age of seedlings.