Syngamy is the fusion of gametes i.e., the union of nuclei of male gamete and female gamete in reproduction process. In angiosperms, generative fertilization is also called, syngamy. In seed plants, the male gametes are brought to the egg containing female gametophyte by a pollen tube. This phenomenon is called, siphonogamy. When pollen tube enters into the ovule through micropyle, is known as porogamy e.g., Lily. When pollen tube enters into the ovule through chalaza, it is known as Chalazogamy e.g., Casuarina.