I just looked at a map of the distribution of Common Milkweed, and there are some counties in OK that have it growing naturally. To find out what types are native to your region, go to Monarch Watch and they have the different species and their regions listed.

Martha

Thanks

Here (NJ/Zone 7), the only variety available from local nurseries seems to be Asclepias incarnata (Swamp Milkweek). I just checked a native plant map for this species. It was shown to be native to every state except those on the West Coast..., and Mississippi?i (well, that's odd) This is the first year I am growing them and am interested in adding other species.