Horse Mint (Agastache rugosa) is a perennial clump-forming mint that grows quite large (3 to 4 feet tall) and produces elongated purple flowers. These are sold as dormant root crowns with a bit of stalk attached, bare root. Photo credit: Qwert1234, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons