LAMIACEAE 



543 



i. M. spicata. 



2. M. piperita. 



3. M. cilrata. 



4. M. longifolia. 



5. M. rolundifolia. 



6. M. alopecuroides. 



7- 



7. L. europaeus L. In waste places: N. Y. to Va. Naturalized 

 from Europe. 



Locally rare as a weed. 



30. Mentha [Tourn.] L. 



Whorls of flowers in terminal spikes, or some in the upper axils. 

 Plants glabrous or very nearly so. 



Spikes slim, narrow, mostly interrupted; leaves sessile, 



or nearly so. 

 Spikes thick, mostly dense, at first short ; leaves petioled. 

 Leaves lanceolate or oblong, acute. 

 Leaves ovate, obtuse, or the upper acute, subcor- 

 date. 

 Plants villous, hirsute or canescent, at least at the nodes. 

 Spikes slim or narrow, often interrupted. 



Leaves lanceolate or ovate-lanceolate, acute. 

 Leaves elliptic or ovate-oblong, obtuse, reticulated 

 beneath. 

 Spikes 10-12 mm. thick, dense, elongated or short. 

 Leaves sessile; spikes 2-8 cm. long; plant canescent. 

 Leaves distinctly petioled, or the uppermost sessile; 

 spikes short. 

 Leaves simply serrate. 



Leaves mostly incised, the margins crisped 

 and wavy. 

 Whorls of flowers all axillary. 



Upper leaves much smaller than the lower. 

 Upper leaves not conspicuously reduced. 

 Stem pubescent. 



Leaves rounded or obtuse at the base. 

 Leaves narrowed, mostly cuneate at the base. 

 Stem glabrous, or very nearly so. 



i . M. spicata L. In moist fields and waste places: N. S. to Ont., 

 Minn., Utah, Fla. and Kan. Naturalized from Europe. 



Locally common as a pasture weed, often wanting; commonly 

 cultivated and often escaping. 



2. M. piperita L. In wet soil: N. S. to Minn., Fla. and Tenn. 

 Naturalized from Europe. 



Throughout most of the range as a weed. 



M. citrata Ehrh. In wet soil: Conn., N. Y. and Ohio. Native 

 of Europe. 



Rare as a weed near New York and in Conn. 



M. longifolia (L.) Huds. In waste places: Conn, to Pa. and 

 N. J. Naturalized from Europe. 

 Occasional as a weed, often wanting. 



M. aquatica. 

 M. oris pa. 



9. M. Cardiaca. 



10. M. arvensis. 



11. M. canadensis. 



12. M. gentilis. 



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