The last hummingbirds of the season are feeding in the jewelweed patch behind Stirling’s Coffee House.

Jewelweed flowers offer nectar to the hummingbirds from a nectar spur at the end of a cone-shaped flower. The hummingbirds have to insert their beaks all the way in to reach the nectar and in doing so they receive a dab of pollen on their foreheads. Many of the hummingbirds in the patch have heads that are completely coated in pollen.

Jewelweed, Impatiens capensis, with nectar spur visible on the far right

The last thing a hummingbird sees before it sinks its beak into the flower. The pollen dusters are at the top of the flower.

Not all spurs are the same shape. Some are curled, others are straight. It turns out the the more curvy spurs result in better pollen transfer to the hummingbirds, probably because the birds have to reach down further to get the nectar.

Compare this piglet-tailed spur to the one above.

The degree of curvature is heritable, so this is a feature that can evolve through natural selection. Why, then, don’t all flowers have the same degree of curl? No-one knows, but the diversity of pollinators that visit jewelweed may favor a diverse set of nectar spur designs.

Bumblebee visiting the same jewelweed patch.

Jewelweed is also called-touch-me-not: a gentle pinch to the bottom of the seed capsule will cause the seeds to explode outwards, shooting several feet away. Gram for gram, the energy stored in these seed pods exceeds that of steel in springs.

Waiting to explode...

As an extra bonus today, the jewelweed patch also hosted a beautiful red phase screech owl. The scolding wrens gave away its location in the shrubs.