MONOPETALOUS EXOGENOUS PLANTS. 411 



nial mostly pubescent or hoary herhs, with erect branch- 

 ing stems; floral leaves Often white-tomentose; cymes 

 mostly terminal, bracted; corolla small, white or pnrj)lish. 

 — Plants aromatic and pungent. 



Calyx-teeth nearly equal. 



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

 bracts ; cymes dense-Jlowered. 



P. ARISTATUM, Michx. Tomeutose and hoary, or some- 

 times 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. Stem li°-3° high; leaves l'-2' long. 



COLLINSONIA, L. Horse-balm. 



Calyx obovate, enlarged and deflexed in fruit, 2-lipped, 

 the upper lip flattened, truncate, 3-toothed, the lower 

 2-cleft; corolla funnel-shaped, 2-lipped, dilated at the 

 throat; the four upper lobes equal, the lowest larger, de- 

 clining, toothed or fimbriate ; stamens 2 or 4, long-exserted, 

 spreading; anther -cells diverging; nutlets smooth. — Strong- 

 scented perennial herbs ; leaves large, coarsely serrate, dot- 

 ted beneath ; flowers yellowish, solitary, opposite, in racemes 

 or panicles ; ^je^jo^es tumid at the base. 



Fertile stamens 4. 



C. ANISATA, Pursh. Viscid pubescent ; stem l°-2° high ; 

 stout, simple or branched; leaves 4-8' long, large, oval or 

 ovate, mucronate-crenate, mostly rounded or cordate at the 

 base, the uppermost sessile; corolla large, yellow; 7M7^?We 

 many-flowered ; bracts ovate ; calyx-lobQ^ large, ovate-lan- 

 ceolate, nearly equal. 



