Flora Antarctica is a fancy name for all the plants that grow in Antarctica, which is a really, really cold place at the bottom of the world. It's so cold there that most plants can't survive, but some really tough ones have adapted to the harsh conditions and managed to make their homes there.
These plants are mostly mosses and lichens, which are like tiny little plants that grow very slowly and in really tough conditions. They have to be super good at surviving in the cold because they only get a few months of sunlight each year, and the rest of the time it's dark and freezing cold.
Scientists have been studying these plants for a while because they're really interesting and there aren't many other places in the world where plants have to deal with such extreme conditions. By studying how they survive, scientists might be able to learn more about how plants adapt to different environments and maybe even use that knowledge to help other plants survive in tough conditions too.