308 LABIATAE 



lobed; anther-bearing stamens 2, distant; the upper pair either 

 sterile or wanting. 



Plants not stoloniferous; calyx-teeth triangular-cuspidate, 



longer than the nutlet. L. americanus. 



Plants stoloniferous at base; calyx-teeth acute, shorter than 



the nutlet. L. uniflorus. 



JLycopus americanus Muhl. Glabrous or puberulent; stems erect, simple 

 orTittle branched, 30-60 cm. high, from creeping rootstocks; leaves lanceolate 

 or Qvate-lanceolate, acuminate or acute, cuneate at base, coarsely serrate or 

 sinuatcly incised, 2-5 cm. long; petioles short; flowers sessile, in dense axillary 

 whorl-liice clusters; bracts subulate; calyx-teeth triangular-cuspidate, stiff, 

 nearly as long as the small white corolla, exceeding the nutlets; sterile stamens 

 slender, with thickened tips. 



In low moist ground, common. 



Lycopus uniflorus Michx. Nearly glabrous; stems erect, 20-60 cm. high, 

 tuberous-thickened at base; stolons more or less tuberous; leaves oblong- 

 lanceolate or lanceolate, acute or acuminate, serrate, attenuate at base, sessile 

 or nearly so, 6-15 cm. long; flower clusters dense; calyx teeth triangular; 

 corolla tubular, 3 mm. long. 



In moist ground, not rare. 



426. MENTHA, Mint. 



P^ Aromatic fragrant perennial herbs; flowers very small, in 

 dense clusters forming false whorls in the axils or in terminal 

 spikes; calyx bell-shaped or tubular, 5-toothed, equal or nearly 

 so; corolla with a short included tube, almost equally 4-cleft, the 

 upper lobe broadest, entire or notched; anther-bearing stamens 

 4, equal, erect, distant. 



Whorls of flowers all axillary. M. canadensis. 

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



Leaves lanceolate, sessile or nearly so; spikes slender. M. spicata. 



Leaves ovate, petioled; spikes thick. M. citrata. 



Mentha canadensis borealis (Michx.) Piper. Wild Mint. Erect, simple 

 or branched, 20-40 cm. high ; stems usually simple, glabrous except in the angles; 

 leaves ovate or broadly lanceolate, mostly acute, rounded or cuneate at the 

 base, sharply serrate, short-petioled, glabrous; flowers in dense sessile axillary 

 clusters; calyx 2-3 mm. long, the triangular acute teeth short; corolla pale- 

 violet, rarely white, 5 mm. long, its lobes rounded, its tube exceeding the 

 calyx. 



In low grounds, common. 



Mentha spicata L. Spearmint. Green and glabrous throughout, the stems 

 30-60 cm. high, simple below the inflorescence; leaves oblong-lanceolate, acute 

 or acuminate, serrate, narrowed to a sessile or short-petioled base, 2-5 cm. long; 

 spikes terminal, narrow, the flowers in interrupted whorls; bracts lanceolate, 

 usually ciliate; calyx hairj', the tube campanulate, little longer than the sub- 

 ulate teeth; corolla purple, its tube exceeding the calyx. 



Common, introduced from Europe. 



Mentha citrata Ehrh. Glabrous or nearly so; stems ascending or erect, 

 30-60 cm. high; leaves ovate, the lower ones obtuse, serrate, petioled, about 



