DICOTYLEDONES. 



201 



Old World. Supplying similarly very narcotic medicines, 



and growing in thesame 

 countries, are also the 

 Heubane (JEyoscyaraus 

 niger) and the Thorn- 

 Apple {Datura stramo- 

 nium). The South 

 American Tobacco 

 {Nicotiana Tabaeum), 

 cultivated by the 

 American aborigines, is 

 31* extensively grown in 



the United States and elsewhere, and used in immense 

 quantities by many nations of the globe. Datura from 

 South America and Mexico, Lydum from Europe, Nie- 

 remhergia (Fig. 314), etc., are cultivated for ornament. 



7. Convolvulaceae, The Convolvulus family has 

 about eight hundred species, in tropical and warm coun- 

 tries generally. They are mostly twining or trailing herbs, 

 often with a milky juice. The corolla is showy and con- 

 volute in the bud. The 

 most important representa- 

 tive is the Sweet Potato of 

 India (Ipomcea Batatas). 

 The Morning-Glory (Fig. 

 315), from Tropical America, 

 is universally cultivated ; s 

 and the twining parasitic 

 Dodder {Ouscuta, Fig. 316), 

 ■with its numerous species, 

 often does much injury to 315 



I Fig. 314, Mierembergisi, a cultivated species. Fig. 315. The Morning-Glory. 



