Sometimes called Giant Horsemint, the Nettle-leaved Giant Hyssop grows in moist meadowy areas. Like other members of the mint family (Lamiaceae), it is aromatic, has square stalks and opposite leaves. The inflorescence is a dense spike at the end of each stalk, with white stamens that reach out from the open tubes of the flowers. The only location I have found Nettle-leaved Giant Hyssop thus far is on the Harsin Butte trail at Zumwalt Prairie, June 27, 2023.