=Wild Mint, Mentha arvensis var. canadensis.=

40b. Leaves glabrous; stem pubescent on the angles only
=Wild Mint, Mentha arvensis var. glabrata.=

41a. Leaves linear; calyx-teeth awl-shape
=Mountain Mint, Pycnanthemum flexuosum.=

41b. Leaves narrowly lanceolate; calyx-teeth triangular-ovate
=Mountain Mint, Pycnanthemum virginianum.=

42a. Stems decumbent to diffuse; leaves cordate to nearly circular
(stems 2-5 dm. long or high; flowers in spring and summer)
(Dead Nettle) --43.

42b. Stem erect; leaves palmately cleft; calyx-teeth spiny (6-15
dm. tall; flowers pink, in summer)
=Motherwort, Leonurus cardiaca.=

42c. Stems erect or ascending; leaves ovate-lanceolate to linear
(summer) --45.

43a. Upper leaves closely sessile (flowers red-purple)
=Dead Nettle, Lamium amplexicaule.=

43b. Leaves all petioled --44.

44a. Flowers red or purple =Dead Nettle, Lamium maculatum.=

44b. Flowers white =Dead Nettle, Lamium album.=

45a. Flowers 2-2.5 cm. long, in loose terminal spikes (5-10 dm. tall;
flowers rose-color) =False Dragon Head, Physostegia virginiana.=

45b. Flowers 1-2 cm. long, in axillary and terminal spiked whorls --46.

46a. Calyx-teeth spiny pointed (flowers pink or pale-purple) (Hemp
Nettle) --47.

46b. Calyx-teeth acute to awl-shape, but not spiny (3-10 dm. high;
flowers pale-purple) (Hedge Nettle) --48.

47a. Leaves ovate (3-8 dm. high) =Hemp Nettle, Galeopsis tetrahit.=

47b. Leaves linear to lanceolate (1-4 dm. high)
=Hemp Nettle, Galeopsis ladanum.=

48a. Leaves glabrous --49.

48b. Leaves distinctly pubescent --50.

49a. Leaves ovate-lanceolate, serrate
=Hedge Nettle, Stachys tenuifolia.=

49b. Leaves linear-oblong, entire or nearly so
=Hedge Nettle, Stachys hyssopifolia.=

50a. Stem pubescent on the angles alone; leaves petioled
=Hedge Nettle, Stachys tenuifolia var. aspera.=

50b. Stem pubescent on both sides and angles; leaves nearly sessile
--51.

51a. Leaves oblong or oblong-lanceolate, more than