Willowherb seed pod
I found the seed pod of this plant in the same meadow where I found the globular coneflower recently:
The plant (an Epilobium spp, maybe Epilobium ciliatum) has slender seed pods that split and curl back in several sections, showing lines of seeds. This pod had just started to open, others had split and curled already. I had no idea what I was looking at, so I posted at the Native Plant Trust (the parent for Garden in the Woods), and a botanist wrote back with the willowherb identification, a plant in the evening primrose family. The curled back pod segments remind me of the evening primrose Oenothera biennis, a cousin of this plant. Now I’ll have to look out for the flower next year.