364 Karl M. Wiegand and Arthur J. Eames 



a. Flowers in dense axillary whorls. 



b. Calyx 1.7 mm. long; corolla 2 mm. long; leaves often blotched with white; 



stems glabrous or with a few scattered hairs. 3. M. gentilis 



b. Calyx 2.5-3 mm. long; corolla 4—5 mm. long; leaves not blotched. 



c. Leaves ovate or ovate-oblong, rounded at base ; stems and leaves hairy. 



4. M. arvensis 

 c. Leaves lanceolate or oblong-lanceolate, acute at base. 

 d. Stems hairy on the sides; leaves hairy. 4a. M. arvensis, 



var. canadensis 

 d. Stems glabrous on the sides, minutely hairy on the angles ; leaves glabrous 

 or glabrate, averaging slightly broader than in no. 4a. 



4b. .1/. arTcnsis, 



var. glabra fa 



1. M. spicata L. (M. viridis of Cayuga Fl.) Spearmint. 



In damp soils of almost any type, but more abundant in calcareous regions ; fre- 

 quent. Aug.-Sept. 



Dwyer Pond; on the flats near Fall Creek; McLean Bogs; shores of Cayuga Lake; 

 near Esty Glen ; and elsewhere. 



N. S. to Ont., Minn., and Wash., southw. to Fla., Tex., and Calif. Naturalized 

 from Eurasia. 



The application of the Linnaean name is very involved (see Rhodora 26:19. 1924). 

 It would seem that Linnaeus intended the name to apply to this plant. 



2. M. piperita L. Peppermint. 



Low gravelly or alluvial stream banks, roadsides, and waste places, mostly in cal- 

 careous regions ; frequent. Aug.-Sept. 



N. S. to Ont. and Minn., southw. to Fla., Tenn., and Ark. Naturalized from Eu. 



An inspection of specimens of M. piperita, from various parts of the world shows 

 this to be a variable species, with leaves narrow or broad, long or short, glabrous 

 or rarely hairy, and with the spikes varying in length and density. Various authors 

 in Europe (for example, Rouy and Foucaud in Flore de France, and Ascherson 

 and Graebner in Fl. Nora 1 , o. Deutsch. Flachl.) interpret M. piperita and M. citrata 

 as hybrids between M. spicata and M. aquatica, and this interpretation seems 

 reasonable. The form taken as typical by Rouy and Foucaud has rather long, 

 lanceolate leaves, and oblong or oblong-linear spikes. This form is infrequent 

 in the wild state in North America, but is the principal peppermint in cultivation. 

 The more common wild form, and the only one in the Cayuga Lake Basin, is 

 intermediate between the form mentioned above as typical and M. citrata, having 

 broader and shorter leaves and shorter spikes than the typical form. The plant 

 listed by Dudley (Cayuga Fl.) as M. piperita, var. subhirsuta Benth., as would 

 appear from a Dudley specimen in the C. U. Herb., has leaves still more like 

 those of il/. citrata or M. aquatica. and the whole plant is villous like M. aquatica. 

 The spikes, however, are like those of the local M. piperita, though the flowers are 

 intermediate in size between those of M. piperita and M. aquatica and the corolla is 

 hair}- outside as in M . aquatica. This form would seem to be another member of the 

 series of hybrids between M. spicata and M. aquatica, or, in this case, possibly a 

 hybrid between M. spicata and -1/. arvensis. 



3. M. GENTILIS L. 



Rich damp gravelly and loamy fields and rich waste places, especially in calca- 

 reous districts ; rare. Aug. 



On the rifle range n. of Fall Creek w. of Ithaca-Drvden town line, 1915 (L. H. 

 MacDaniels) ; near Ringwood, 1917 (A. R. Bechtel & K. M. IV.). 



P. E. I. and n. N. Y. to Iowa, southw. to Ga., N, C, and Tenn. Naturalized 

 from Eu. 



