I've just pushed a patch to the experimental update based on an idea from the discord community.
When a seed lands the slope of the landscape is checked, based on some genes I won't reveal, if the slope is too steep (like on the sides of the maps) the plant will not grow.
This should stop all the weird looking plants on the map edges and will also add some interesting evolutionary strategies for the plant genes!
Let us know what you think! The change only effects new plants, so existing plants in your game saves won't be effected.
Edit: This is now live on the main branch.