If I was certain that the highway dept mowed that area, I would try to get a picture to make sure the plant wasn't endangered in any way other than the mowing machines and then collect the plant. Otherwise, I would watch carefully for the seed pods to ripen from green to brown and collect a single pod. They are usually full of seeds, so one would do it. In this link, enter Asclepias and check the box for Michigan. That shows what milkweed plants grow in your state.
http://plants.usda.gov/checkli...
This was a gift from the birds here
plant
seeds
plant
seeds
