h)
--18.

18a. Corolla distinctly surpassing the calyx in length (spring and
summer) =Corn Gromwell, Lithospermum officinale.=

18b. Corolla equaling or shorter than the calyx (spring)
=Wild Gromwell, Lithospermum latifolium.=

LABIATAE, the Mint Family

Herbs with opposite leaves, square stems, and usually aromatic odor;
flowers irregular, with united petals, or almost regular; stamens 2 or
4, attached to the tube of the corolla; ovary deeply 4-lobed, with a
single style.

1a. Stamens 2 --2.

1b. Stamens 4 --15.

2a. Corolla regular or nearly so; flowers white, in dense axillary
clusters; plants usually of wet grounds (2-8 dm. high; summer
and autumn) --3.

2b. Corolla distinctly irregular and more or less 2-lipped --7.

3a. Calyx-teeth short, triangular, acute or obtuse (Bugle Weed) --4.

3b. Calyx-teeth narrow, acuminate or cuspidate (Water Hoarhound) --5.

4a. Stems and stolons bearing tubers
=Bugle Weed, Lycopus uniflorus.=

4b. Stems and stolons not bearing tubers
=Bugle Weed, Lycopus virginicus.=

5a. Leaves serrate; calyx-teeth sharp-pointed --6.

5b. Leaves coarsely incised; calyx-teeth awn-tipped
=Water Hoarhound, Lycopus americanus.=

6a. Corolla twice as long as the calyx; leaves narrowed at the base
=Water Hoarhound, Lycopus rubellus.=

6b. Corolla barely longer than the calyx; leaves sessile or nearly
so =Water Hoarhound, Lycopus lucidus var. americanus.=

7a. Corolla blue, 3-4 mm. long; flowers in loose axillary clusters (1-4
dm. high; summer) (Pennyroyal) --8.

7b. Corolla 8-40 mm. long --9.

8a. Leaves serrate =Pennyroyal, Hedeoma pulegioides.=

8b. Leaves linear, entire =Pennyroyal, Hedeoma hispida.=

9a. Lower lobe of the corolla fringed, very much longer than the upper
(5-15 dm. high; corolla pale-yellow; late summer)
=Horse Balm, Collinsonia canadensis.=

9b. Lower lobe of the corolla nearly or quite as long as the upper and
not fringed --10.

10a. Calyx narrowly tubular; its teeth about equal in size (5-10
dm. high; flowers in dense terminal heads, in summer) --11.

10b. Calyx campan