A sex organ (also called a reproductive organ, primary sex organ or primary sexual characteristic) is any anatomical part of the body in a complex organism that is involved in sexual reproduction and together constitute the reproductive system.The external and visible organs, in males and females, are the primary sex organs known as the genitals or genitalia.The life cycle of land plants involves alternation of generations between a sporophyte and a haploid gametophyte.
In a larger perspective, the whole process of sexual differentiation also includes development of secondary sexual characteristics such as patterns of pubic and facial hair and female breasts that emerge at puberty.
The seed plants, which include conifers and flowering plants have small gametophytes that develop inside the pollen grains (male) and the ovule (female).
Sexual reproduction in flowering plants involves the union of the male and female germ cells, sperm and egg cells respectively.
The sporophyte produces spores by meiosis which in turn develop into gametophytes.
Any sex organs that are produced by the plant will develop on the gametophyte.