Hello again!
After discussing your idea, we have unfortunately decided to decline it as it would likely make the map become very cluttered. Furthermore, adding more icons would cause the map to become slower than it already is which would be annoying. It would also remove the aspect of exploration because currently getting plants/herbs is fairly easy, so there should be some kind of challenge and that is exploring and finding their locations.
We also do not think adding plants to the map is too necessary because players can also help each other by asking each other in chat or creating and sharing spreadsheets like Nathan has. This is something we definitely encourage players to do!
Nevertheless, thank you for mentioning your idea. We really do appreciate any suggestions or feedback that the player base brings up to us!
Thanks and have a great day!