The male sex organ of a flower is known as the stamen. The stalk is called the filament and it holds up the anther. Anthers contain usually four microsporangia. Inside, meoisis occurs forming haploid spores. These divide by mitosis to form an immature microgametophyte. This is also known as a pollen grain. When the anther opens, pollens are released. Eventually, they will land on top of the pistil, the female part of a flower. This is called pollination. Next, the pollen grain germinates down towards the ovary, by forming a pollen tube. Mitosis occurs and two male gametes called sperm are the result. One sperm will unite with an egg or ova inside the ovary to form a zygote. The other sperm will unite with two polar cells to form a triploid tissue called endosperm, which will nourish the developing seedling. Therefore, the answer to your original question is pollen.