yeah moss is great but how about a vascular plant that has basically ... gone back to the way of the moss...
Azorella compacta
It's... it's a carrot that has given up on having leaves...
Imagine a hostile planet with plants like this... could you tell that they once grew in less cold and arid climates? What if flora of the twilight days of a planet look like the earliest life... but when you look closer there are abilities, and structures that tell their history....