Even native plants can be considered weeds if they interfere with the management plans of humans. Because certain milkvetches are poisonous to livestock, they may find themselves being weeded out of pastures and rangelands. These plants have earned the name locoweeds, because of the conditions they cause in the animals that eat them.
Sunflowers, on the other hand, don’t get the same bad rap. For starters, they aren’t toxic to cows. Beyond that, they are ecological powerhouses that provide food for a wide variety of organisms. Plus they are drought tolerant and easy to grow. Like Casey says, they are a “win-win!”