I'm surprised that they chose 3 pretty complex plants. The duckweed seems like the best idea, but wouldn't it be more useful at this point to be experimenting w

I'm surprised that they chose 3 pretty complex plants. The duckweed seems like the best idea, but wouldn't it be more useful at this point to be experimenting with more primitive components of an ecosystem rather than full-fledged plants? Like algae and fungus and phytoplankton. It just seems like the question of whether a plant can survive and grow at all on the moon is not that different from whether a human can survive on the moon, and we already know that humans do pretty ok for limited time as long as you keep them in their spacesuits. I guess this is just figuring out what is required for a "plant spacesuit" to start working on extending how long one can last. I guess it's a top-down vs bottom-up philosophy, or something. I mean, even starting with phytoplankton, we'll have to provide missing nutrients. So it's not like you can just genetically engineer phytoplankton into terraforming the moon on their own. Unless you can figure out how to genetically engineer in a little nuclear reactor so the plants can produce their own missing elements...