Asclepias speciosa

Showy Milkweed. The meadow through which I ride my bike to work is full of these flowering plants right now; daily I'm treated to this beauty many times over.

Milkweeds are heavily associated with the Monarch Butterfly and its brush-footed cousins. The nectar of the flowers makes up a large portion of an adult's diet, and the larvae, which are always deposited on milkweed, consume nothing but the leaves. This is a fascinating and highly effective survival strategy, in that the larvae (and adults) incorporate the poisonous glycosides of the plant into their own system, making them toxic in their own right, and therefore unappetizing to would-be predators.