Male gametes in flowering plants, also known as sperm, form within the pollen grain.

Here's a breakdown:

* Pollen grains are produced in the anther of the stamen, which is the male reproductive part of the flower.

* Inside each pollen grain, there are two cells:

* Generative cell: This cell divides mitotically to produce two sperm cells.

* Tube cell: This cell develops into the pollen tube, which grows towards the ovule to deliver the sperm cells.

So, the male gametes (sperm cells) are ultimately formed within the pollen grain, but their development begins in the generative cell within the anther.