I have not weed out my island, because I like the weeds. They are nice looking plants, and without them, the terrain would look flat, and less interesting. So I'm keeping them. I can also say with some level of certainty that they have not reproduced/spread. It might have to do with the fact that my island is already full of them since I first landed on it about 10 days ago.
But what about you? Did you see them spread or spawn on your island? How do they behave?
But what about you? Did you see them spread or spawn on your island? How do they behave?