|Photographed 17 July 2014, Cinder Path prairie remnant east of Derby, Iowa.|
Pycnanthemum tenuifolium. No mountains in sight, but native to Lucas County and other southern Iowa upland black dirt prairies; rare farther north. Grows 1-3 feet tall with short narrow leaves and frequent branching. profuse clusters of small tubular white flowers appear mid- to late July.
Plants, when crushed fresh or dried, have a strong, pleasant minty scent.