1. Primary leaves sharply serrate to serrate-dentate; stem glabrous or essentially 



so; calyx teeth and tube subequal, glabrous, the teeth straight 



var. rubellus. 



1. Primary leaves with low and depressed teeth; younger internodes and lower 

 surfaces of leaves pubescent; calyx teeth often with recurving tips 

 var. arkansanus (Fresen.) Bermer. 



14. Mentha L. Mint 



Odorous perennial rhizomatous herbs with erect or diffuse stems; leaves sessile 

 or petioled, usually punctate; flowers small, in whorls that are axillary or in 

 terminal congested or interrupted spikes, of two sorts as to the fertility of the 

 stamens in most species; calyx campanulate to cylindric, 10-nerved, regular or 

 slightly bilabiate, 5-toothed: corolla pale-purple or whitish, bilabiate, the tube 

 shorter than the calyx, the upper lip entire or emarginate, the lower lip 3-lobed; 

 stamens 4, equal, erect, included or exserted; filaments glabrous; anther sacs 

 parallel; ovary 4-parted; style 2-cleft at the summit; cocci ovoid, smooth. 



About 25 species in the North Temperate regions. 



The seeds are eaten by waterfowl and game birds, and the succulent rhizomes 

 are known to be eaten by muskrats. 



1. Flower whorls all distant and in leaf axils; leaves exceeding the whorls 



1. M. arvensis. 



1. Flower whorls forming terminal spikes or some of the lower in the leaf axils 



and somewhat distant (2) 



2(1). Plants tomentose or villous-tomentose; leaves sessile 2. M. rotundifolia. 



2. Plants glabrous or nearly so; leaves more or less petiolate (3) 



3(2). Leaves short-petioled to nearly sessile; spike slender, more or less inter- 

 rupted 3. M. spicata. 



3. Leaves all distinctly petioled; spikes thick and mostly dense 4. M. piperita. 



1. Mentha arvensis L. Field mint. Fig. 676. 



Plant aromatic; stems stoloniferous, freely branching below or nearly simple, 

 to about 8 dm. high, more or less retrorse-pubescent (especially on the angles); 

 leaves oblong to ovate or lanceolate, rounded at base to a distinct petiole, usually 

 rather closely serrate, minutely pubescent or short-villous, the larger leaves to 

 about 5 cm. long, the upper leaves not much smaller than the lower ones; flower 

 whorls all axillary; calyx pubescent, about 3 mm. long, the triangular-subulate 

 teeth about equaling the tube; corolla pink to violet or white, about twice as 

 long as the calyx, nearly or quite glabrous. Incl. var. villosa (Benth.) S. R. Stewart 

 and var. glahrata (Benth.) Fern., M. Penardii (Briq.) Rydb., M. canadensis L. 



In moist rich soils, cat-tail swamps, seeping wet meadows, marshes, about 

 lakes, springs and along ditches and streams, in w and n.w. Tex., N. M. (Colfax, 

 Otero, Rio Arriba, San Juan, Sandoval, Union, Taos, San Miguel and Catron 

 cos.) and Ariz., (Apache, Navajo, Coconino, Yavapai, Greenlee, Santa Cruz and 

 Cochise cos.), May-Oct.; circumboreal. 



2. Mentha rotundifolia (L.) Huds. Applemint, roundleaf mint. Fig. 677. 



Perennial with leafy stolons, the herbage more or less tomentose and viscid; 

 stems mostly erect, to about 15 dm. high, simple or branched; leaves sessile 

 or short-petioled, elliptic to ovate- oblong, subcordate to rounded at base, obtuse 

 at apex, the larger leaves to 5 cm. long, crenate-serrate, more or less rugose- 

 reticulate beneath; flower whorls approximate or the lower especially somewhat 

 distant, forming rather slender spikes to 1 dm. long in fruit; bracts ovate-lanceo- 

 late to lanceolate, acuminate, usually shorter than the flowers; calyx campanulate, 

 greenish, velvety, barely 2 mm. long, the subulate teeth about as long as the tube 

 and connivent in fruit; corolla white or pink, about 4 mm. long, puberulent. 



1443 



