When male and female plant reproductive cells join, they form a zygote.

Here's a breakdown:

* Male reproductive cell: This is called a sperm cell or pollen grain.

* Female reproductive cell: This is called an egg cell or ovule.

* Zygote: The zygote is the first cell of a new plant. It contains genetic material from both the male and female parent plants.

The zygote will then undergo cell division and development to eventually become a mature plant.