314 LABIATE. (MINT FAMILY j 



6. PYCNANTHEMUM, Michx. HORSE-MINT. 



Calyx tubular, 13-nerved, naked in the throat, equally 5-toothed, or slightly 

 2-lipped. Corolla 2-lipped ; the upper lip notched or entire, the lower 3-cleft. 

 Stamens 4, nearly equal, straight, spreading, commonly exserted : anther-cells 

 parallel. Style 2-cleft at the apex. Nutlets smooth. Perennial mostly pu- 

 bescent or hoary herbs, with erect branching stems. Floral leaves often white- 

 tomentose. Cymes mostly terminal, bractcd. Corolla small, white or purplish. 

 Plants aromatic and pungent. 



* Calyx mare or less 2-lipped, the subulate teeth often bearded with weak jointed hairs : 

 cymes mostly terminal, widely Dreading in fruit : bracts longer than the flowers : 

 leaves pubescent, the uppermost whitened. 



1. P. incanum, Michx. Stem densely pubescent and hoary ; leaves ovate 

 or oblong-ovate, acute, sharply serrate, short-petioled, hoary-tomentose beneath ; 

 calyx-teeth subulate, and, like the bracts, commonly bearded with weak hairs. 

 (P. Loomisii, Nutt.) Var. TULLIA. (P. Tullia, Benth.) Leaves smaller and 

 smoother; cymes larger and more expanded; calyx-teeth longer. Var. AL- 

 BESCENS. (P. albescens, Gray.) Leaves ovate-lanceolate, obtuse, smooth above, 

 hoary beneath ; calyx-teeth triangular lanceolate, obtuse, not bearded. Dry 

 woods and fence-rows, Florida to Mississippi, and northward. Aug. and Sept. 

 Stem 2 - 4 high. Leaves 1 ' - 2' long. Flowers white. 



2. P. dubium, Gray. Stem villous-pubescent ; leaves lanceolate, acute 

 at each end, smooth or nearly so, entire ; cymes hoary, dense-flowered, short - 

 peduncled ; calyx-teeth subulate, tipped, like the bracts, with a tuft of weak 

 hairs ; the 2 lower ones shorter. Mountains of North Carolina. Aug. and 

 Sept. Stem 2 - 3 high. Leaves 2' - 3' long. 



* * Calyx-teeth nearly equal, 



H- Calyx as long as the corolla ; the teeth subulate and awn-pointed, like the rigid 

 bracts : cymes dense-flowered 



3. P. aristatum, Michx. Tomentose and hoary, or sometimes hairy ; 

 stem branched ; leaves ovate or oblong, acute, sparingly serrate, rounded at the 

 base, short-petioled, the uppermost somewhat whitened ; cymes mostly terminal ; 

 ovary bearded. Var. HYSSOPIFOLIUM, Gray. Stem simple or corymbose 

 above; leaves rigid, linear-oblong, obtuse, entire. Low ground, Florida to 

 Mississippi, and northward. Aug. and Sept. Stem l-3 high. Leaves 

 l'-2' long. 



^_ ^_ Calyx-teeth beardless and awnless : cymes capitate, mostly terminal : bracts 

 shorter than the flowers : leaves subsessile. 



4. P. pilosum, Nutt. Softly pubescent or villous ; branches short, erect , 

 leaves lanceolate, entire, acute at each end, none of them whitened ; cymes 

 small, compact, corymbose ; calyx-teeth ovate-lanceolate, acute, and, like the 

 bracts, hoary-tomentose, or, in var. LEPTODON, Gray, subulate and villous. 

 Upper districts of Georgia, and northward. Aug. and Sept. Stem 2 high. 

 Leaves l'-2' long. . 



