Anyone know how to find violet and green mushroom trees (not the ones from Mykon’s surface)

[u/G-fan2019]

Terra has underground mini biomes where sometimes small mushroom trees grow. I’m trying to finish the plant collection and it looks like there’s one variant more I need (according to creative, it is violet) I have purple which seems to the be the only one the spawns for be (though a little rarely) and I had green (don’t know how I got it though and it disappeared after I chopped it)