I have a most fascinating milkweed in my garden. It is Asclepias physocarpa milkweed. This milkweed has several common names, such as Balloon plant and Oscar milkweed. Compared to the other types of milkweeds, this is a rather unique one. Plus, clearly it is one of the more favored host plants of the Monarch.
The day I took the accompanying photos, I stopped counting at over 30 larvae on my plant. I first discovered this milkweed last year after seeing a plant that had been completely stripped to nothing but bare stems with the larvae resorting to eating the seed pods.