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To see a field of common milkweed in midsummer — a sea of a thousand nodding pink flower heads — you would not imagine that anything could ever stand in the way of the genus Asclepias.

Asclepias produce potent steroids called cardenolides “that can disrupt the life functions of vertebrate animals unlucky enough to feed on them,” he adds.

Their larvae rely on Asclepias as an obligate host plant, or a food required for at least one stage of development.

Beyond so many opportunities for herbivory, Asclepias flowers provide nectar to adult butterflies and moths, along with an astonishing lineup of bee species and wasps.

Although the palette of Asclepias is generally quite different from East to West, “tuberosa is one that crosses the Continental Divide,” he said, residing even in parts of the desert Southwest.