SPECIES AND VARIETIES. 289 



those of the stem in distant pairs, perfoliate ; flowers bright 

 yellow, in terminal cymes, the corolla nearly rotate. Yellow- 

 wort. Dry pastures and waste places, in limestone districts. 

 Fl. July, August. 



(207) Villarsia. 



V. nymphseoides : aquatic ; stems creeping and rooting at 

 the base, branching and ascending to the surface of the water, 

 bearing a single leaf at each upper branch, and a terminal 

 floating tuft of leaves and peduncles; leaves long-stalked, 

 deeply cordate ; peduncles terminated by a rather large yellow 

 flower. Ponds and still waters. FL July, August. 



(208) Datura. THORN-APPLE. 



D. Stramonium : annual ; stems coarse, glabrous, 1-2 feet 

 high, with spreading, forked branches; leaves large, ovate, 

 with irregular angular teeth; flowers solitary, on short pe- 

 duncles, in the forks or at the ends of the branches; calyx 

 loosely tubular; corolla white, fragrant; capsule roundish- 

 ovate, very prickly, with numerous wrinkled seeds. A road- 

 side weed, but scarcely naturalized. Fl. July. 



(209) Hyoscyamus. HENBANE. 



H. niger : annual or biennial, hairy, viscid, with a nau- 

 seous smell: annual plants erect, about one foot high, the 

 leaves sessile, the upper ones clasping the stem, ovate, irre- 

 gularly pinnatifid : biennial plants producing a tuft of large, 

 stalked, elliptic, radical leaves which perish, and in the follow- 

 ing year a coarse branched stem 1-2 feet high ; flowers in one- 

 sided leafy spikes,rolled back at the top before flowering; calyx 

 persistent round the fruit, strongly veined, with five stiff, broad, 



