Asclepias syriaca, Common Milkweed, is a well know menace among farmers. A single plant quickly sends up root suckers in an ever increasing network of roots. The air born seeds allow them to spread around quickly too.
Personally I've grown this species for the past 4 years and I've found it to be fairly tame. Granted it's not getting a whole lot of sun but enough to call it full sun. It's in heavy clay that doesn't drain very well. So it's not imposable to grow it in a garden.
Asclepias tuberosa (seen above), and
Asclepias incarnata are more garden friendly though.
A. incarnata is fragrant too which a lot of people don't know about! Whenever the flowers are in the sun they smell like a generic desert, reminiscent of fresh cup cakes out of the oven.
Common Milkweed flowers come in a lot of shades, partly depending on the age of the flower. Here are some deep purple ones.
Almond and Cream colored. There were lots of ants stealing nectar from the flowers. As well as bees and beetles pollinating them legitimately.
A rainbow of colors.
One plant I noticed had some clusters as this solid white color, as well as the deep purple, which was odd because the clusters were so close to one another.
