MINT FAMILY 661 



equaling the tube, ciliate on the margins, the inflorescence otherwise glabrous; corolla pale 

 lavender. 



Moist fields and meadows, Upper Sonoran and Transition Zones; Washington, on both sides of the Cascade 

 Mountains, south to southern California, and eastward to the Atlantic Coast. Naturalized from Europe. 

 July-Oct. 



2. Mentha piperita L. Peppermint. Fig. 4457. 



Mentha piperita L. Sp. PI. 576. 1753. 



Perennial by underground sometimes leafy-bracted stolons ; stems erect or somewhat decum- 

 bent, branched, 3-8 dm. high, often purplish. Leaves lanceolate to ovate-lanceolate, dark green 

 and firm, glabrous or sparsely pubescent on the veins beneath; whorls of flowers in terminal, 

 dense or interrupted spikes, 2-12 cm. long in fruit; bracts narrowly lanceolate, acuminate, not 

 surpassing the flowers ; calyx-tube glabrous, the teeth about equaling or shorter than the tube, 

 hirsute, sometimes sparingly so, ciliate; corolla glabrous, rose-purple to white. 



Wet places, mainly in the Transition and Upper Sonoran Zones; Washington to southern California, and 

 eastward across the continent. Naturalized from Europe. July-Oct. 



3. Mentha citrata Ehrh. Bergamot Mint. Fig. 4458. 



Mentha citrata Ehrh. Beitr. 7: 150. 1792. 



Perennial by leafy-bracted stolons, glabrous throughout; stems decumbent or ascending, 3-6 

 dm. long, usually purple. Leaves slender-petioled, ovate to round-ovate, obtuse or the upper 

 acute at apex, rounded or subcordate at base, thin, rather shallowly serrate, the larger about 5 

 cm. long ; whorls of flowers in thick dense terminal spikes, and frequently also in the upper leaf- 

 axils ; spikes usually 2-2.5 cm. long at maturity; calyx-teeth subulate, glabrous, shorter than 

 the tube; corolla rose-colored, about twice as long as the calyx. 



Moist ground; sparingly established in the Pacific States, from western Washington to California. Nat- 

 uralized from Europe. July-Nov. 



4. Mentha rotundifolia (L.) Huds. Apple Mint. Fig. 4459. 



Mentha spicata var. rotundifolia L. Sp. PI. 576. 1753. 

 Mentha rotundifolia Huds. Fl. Angl. 221. 1762. 



Perennial by leafy stolons, herbage more or less tomentose and viscid; stems mostly erect, 

 5-15 dm. high, simple or branched. Leaves elliptic to ovate-oblong, sessile or short-petioled, 

 subcordate or rounded at base, obtuse at apex, the larger 2.5-5 cm. long, crenate-serrate, more 

 or less rugose-reticulate beneath; flower- whorls forming rather slender spikes, approximate or 

 the lower especially somewhat distant, becoming 5-10 cm. long in fruit; bracts lanceolate, acumi- 

 nate, usually shorter than the flowers ; calyx campanulate, barely 2 mm. long, the teeth subulate, 

 about as long as the tube ; corolla white, about 4 mm. long, puberulent. 



Sparingly naturalized in the Pacific States from western Oregon to southern California. Native of Eu- 

 rope. Round-leaved mint. Horse mint. June-Oct. 



5. Mentha alopecuroides Hull. Woolly Mint. Fig. 4460. 



Mentha alopecuroides Hull, Brit. Fl. 126. 1799. 



Stems stout, stoloniferous, 5-10 dm. high, leafy; herbage white-woolly. Leaves broadly oval 

 to oblong-ovate, sessile or somewhat clasping by a subcordate or rounded base, obtuse at apex, 

 sharply serrate, the larger 4-7 cm. long; flower-whorls in several stout dense terminal spikes 

 4-8 cm. long in fruit ; calyx canescent, 2 . 5 mm. long, the narrowly subulate teeth about equaling 

 to twice as long as the tube ; corolla pink, 5 mm. long, pubescent. 



Snaringly established as an escape from cultivation in western Washington and Oregon. Native of Europe. 

 July-Oct. 



6. Mentha Pulegium L, Pennyroyal. Fig. 4461. 



Mentha Pulegium L. Sp. PI. 577. 1753. 



Stems in younger plants erect and simple below, arising from a short usually horizontal root- 

 stock, in older plants more or less decumbent, 3-6 dm. high, branches arise from the nodes of 

 the rootstock or the base of the stem, herbage canescent with a short-villous pubescence. Leaves 

 1-2 cm. long, elliptic to oblong-ovate, serrate or entire, tapering at base to a short petiole, or 

 the uppermost reduced and subsessile, spreading or often recurved ; flower-whorls often numer- 

 ous, rather distant, the subtending leaves, especially of the upper whorls, reduced and bract-like, 

 subsessile ; pedicels scabrous ; calyx hirsute on the nerves and teeth, the two lower teeth narrower 

 and longer than the three upper ones, the throat conspicuously white-villous within ; corolla 

 lavender, about twice as long as the calyx, the lobes conspicuously villous on the outside. 



Low moist ground, mainly Upper Sonoran Zone; rather sparingly naturalized in the Pacific States from 

 western Oregon to southern California. Native of Europe. June-Oct. 



7. Mentha arvensis L. Field Mint. Fig. 4462. 



Mentha arvensis L. Sp. PI. 577. 1753. 



Stems stoloniferous, freely branching below or nearly simple, 1-8 dm. high, more or less 

 retrorse-pubescent, especially on the angles. Leaves oblong to ovate, rounded at base to a distinct 



