Key to Wisconsin Lycopus

Author: John G. Zaborsky

• 1a. Calyx lobes obtuse to acute at the tip, shorter than or barely equaling the nutlets; plants often producing elongate surficial runners 2

• 1b. Calyx lobes acuminate to subulate at the tip, distinctly longer than the nutlets; plants lacking runners (but may be rhizomatous) 3

• 2a. Plants arising from soft tubers; stamens exserted from the corolla tube; calyx and corolla each with 5 lobes; nutlets with tubercles or teeth only along the outer rim; leaf blades lanceolate to ovate-lanceolate L. uniflorus

• 2b. Plants without tubers; stamens included; calyx and corolla each with 4(–5) lobes (the adaxial corolla lobe sometimes notched); nutlets with tubercles or teeth across the entire surface; leaf blades ovate L. virginicus

• 3a. Leaves sessile with a regularly serrate margin; nutlets tuberculate on the apex L. asper

• 3b.Leaves petiolate to subpetiolate, prominently dentate (or narrowly lobed toward the base); nutlets with a smooth corky rim along the outer margin of the apex 4

• 4a. Lower leaves often deeply pinnatifid into liner lobes, the teeth (or lobes) mostly with the forward margin at an acute angle to the midrib; leaves glabrous (or merely scabrous) above; hairs on abaxial leaf surfaces <0.5 mm="" long="" calyx="" 2="" 0="" 3="" span=""> L. americanus

• 4b. Lower leaves coarsely dentate, forward margin of the teeth at a ± right angle to midrib; leaves strigose above; hairs on abaxial leaf surfaces >0.5 mm long; calyx 3.0–4.5 mm long L. europaeus