Milkweed Flower

Monarch Butterflies depend on the milkweed for their larval stage food, yet milkweed doesn't grow in the parts of Mexico and California where they hibernate in the same trees every year, so they can't begin reproducing until they head north in the spring.  This milkweed flower looks like it's providing food for some of the ants in Shenandoah National Park, as well as possibly hosting some Monarch caterpillars (no I didn't see one.)

It's interesting that they hibernate in the same exact trees every year, yet this winter's crop will be three or four generations removed from last year's crop.