Honeybee feeding on water willow, Duck Hollow, 27July 2025 (photo by Kate St. John)

28 July 2025

Yesterday morning was so muggy that Charity Kheshgi and I went to Duck Hollow hoping for a cool breeze. Even at the water’s edge there was very little breeze but there were cool flowers.

From a distance American water willow (Dianthera americana) looks like common green stuff growing at the water’s edge. Through binoculars I could see that Duck Hollow has a lot of it, even more than marked on this photo.

Location of water willow at Duck Hollow (markup), end of July 2025 (photo by Kate St. John)

Water willow has to have its feet wet.

The creeping rhizome allows Dianthera americana to form large colonies on or near the shorelines of still or slow waters in lakes and rivers, and on rocky riffles and shoals in faster flowing rivers. Its rhizomes and roots provide important spawning sites for many fish species and habitat for invertebrates.

The leaves resemble willow but unlike real willows this plant never gets more than three feet tall. Its dense vegetation and rhizomes help reduce shoreline erosion.

Typical water willow , Justicia americana (photo from Wikimedia Commons)

From a distance the small white and purple flowers, only 1.5 inches across, are difficult to see. Up close they are beautiful, almost like irises, and their purple markings lure in pollinators. The clump we examined was humming with honeybees, shown at top.

Closeup of water willow flowers, 27 July 2025 (photo by Kate St. John)

We also saw a tiny new-to-us moth. Through iNaturalist my guess is it’s an orange-banded Tripudia moth (Tripudia flavofasciata). … Is it?

Orange-banded Tripudia moth (?) feeding on water willow, Duck Hollow, 27July 2025 (photo by Kate St. John)

If you live near water in eastern North America chances are good that you have water willow near you. Blooming from summer to fall it is common within its wide range.

Range of American water willow (map from Wikimedia Commons)