MONOPETALOUS EXOGENOUS PLANTS. 391 



bell-shaped, open at the throat, bilabiate ; the upper lip 

 rounded, concave, emarginate or 2-lobed ; the lower lip 

 3-lobed ; stamens 4, declined at the base, and a fifth sterile 

 one as long as the others, and commonly bearded above ; 

 capsule 2-valved, many-seeded ; seeds wingless. — Erect 

 perennial he7'hs, with opposite leaves, and white or purple 

 jloivers in axillary and terminal cymes, forming a close or 

 open narrow terminal panicle. 



* Leaves undivided. 



P. PUBESCENS, Solander. Pubescent or smooth ; leaves 

 lanceolate, acute, serrate or entire, sessile or clasping, the 

 lowest ovate or oblong, tapering into a slender petiole ; 

 cymes spreading; few-flowered; tube of the cor o?^« grad- 

 ually dilated above the middle; the lower lip longer than 

 the upper; sterile stamen bearded down one side; anthers 

 smooth. Stem 2° high ; lowest leaves 3-5' long ; corolla 

 1' long, pale purple. 



P. GRANDiFLORis. Found on the Red River by Marcy's 

 Expedition. — Torrey, 



LINARIA, Juss. Toad-flax. 



Calyx deeply 5-parted; coroZ?a personate, spurred at the 

 base ; the upper lip emarginate or 2-lobed ; the lower 

 3-lobed ; the throat commonly closed by the prominent 

 palate; 5^rtme?z5 4, didynamous; capsule globose or ovoid, 

 opening at the apex, with few or several tooth-like valves, 

 many-seeded. — Herls, with alternate or (on the radical 

 branches) opposite or whorled leaves, and axillary or race- 

 mose ^oz(;er5. 



* stems tcith prostrate branches at the base, which bear broader opposite or whorled 



leaves. 



L. Canadensis, Spreng. Smooth ; stem erect, slender, 

 mostly simple ; leaves linear, flat, scattered, those on the 

 radical branches oblong ; racemes straight ; pedicels erect. 



