Smell of Success

“Its flowers are very fragrant and when in season, they fill the woods with their sweet exhalations and make it agreeable to travel in them, especially in the evening”. Pehr Kalm

The famous Swedish scientist and colleague of Linnaeus wasn’t wrong–humans and insects alike are drawn to the intoxicating perfume of common milkweed (Asclepias syriaca) at this time of year. It’s like an ice-cream stand for pollinators–the fragrance is an unmistakable promise of a rich, sweet summertime reward!

But the unusual structure of this native is worth a closer look. Each milkweed ‘flower’ is really a group of many small, individual flowers, composed of five hoods and horns clustered around a base. Unlike many other flowers that plainly offer their nectar and the loose, powdery pollen grains most of us are familiar with seeing, milkweed pollen is packed into two connected sacs (pollinia) within each flower that resemble tiny saddlebags. When a pollinator visits a flower cluster, its leg may slip into the crevice of one of the individual flowers and become entangled with the pollinia (look carefully at the photo!).

If they’re lucky, the pollinator will be able to free themselves, taking the pollinia with them as they head to another flower. Bees, those super-efficient pollinators, will move a larger number of pollinia, distributing it all around the neighborhood. But butterflies such as monarchs, who carry less of this precious cargo, may distribute them much farther–perhaps over many miles!

Whether enjoyed by bee, butterfly, wasp or human, the sweet scent of milkweed can be a good reminder of the untold wonders of our natural world.

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