Morphological Differentiation of Male Flower Bud of Ginkgo biloba L. The Mixed Inheritance Analysis of the Nodal Position for First Female Flower Bud in Luffa (Luffa cylindrica Roem. ) Morphological Differentiation of Male Flower Bud of Ginkgo biloba L. Changes of Endogenous Hormones,Carbohydrate and Mineral Nutritions during the Differentiation of Male Flower Buds in Ginkgo biloba