314 labiatjE. (mint family) 



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, bracted. Corolla small, white or purplish. 

 — Plants aromatic and pungent. 



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

 cymes viostly terminal, ividely spreading 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, Natt.) — Var. Tullia. (P. TuUia, 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. 



■I- Calyx as long us the corolla ; the teeth subulate and awn-pointed, like the rigid 



bracts : cymes dense flowered- 



3. P, aristatuni, 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 1'- 2' long. 



