Russian Olive Trees
The previous owner that we bought our house from had a slew of trees, bushes, shrubs, and other plants growing in the yard. Someone mentioned that we have a Russian Olive tree. Then, I was told that they were illegal now. I think that they are illegal to sell and buy, but what if it is fully grown in the backyard and we never planted it there in the first place?
I did see that it is not legal to sell or purchase in Colorado.
It is considered hight invasive so it is not a good plant.
You would not be responsible for an existing mature tree. These laws apply to the sale of seedlings.
Here are a few links for you.