Canada milkvetch was collected in our county in 1866, and again by Cecil Billington in 1916. He described it as "frequent, south of Tecumseh". I have spent a lot of time tromping around south of Tecumseh in the last 40 years. If milkvetch is there, it's anything but assertive.
I've never been too fond of all the beautiful milkvetches. It's not their fault. An astragulus is also a mammalian ankle bone. I can still remember being asked to identify a camel's astragalus on a comparative anatomy lab exam. What an unfair question! Curious what you still remember after half a century.