Is there a case of Invasion of the Body Snatchers in our back yard?
Nope! No worries - these are just the seed pods of what I believe is butterfly weed. I think I remember the flowers on these wild plants just at the back edge of our yard looking like butterfly weed. I know I remember each leaf usually having 1-2 large black ants patrolling it. Didn't really notice any Monarch butterflies attracted to it, but I didn't see many of those around this year anyhow. The swallowtails seemed more attracted to our butterfly bush instead of the butterfly weed (two different plants).
Shouldn't be too much longer before these pods pop open and big tufts of fluff come floating out of them...spreading the seeds around for next year.