248 



BORAGINACEM. 



[chap 



The Sweet Potato [Batatas edulis) is cultivated everj^vhere 

 in tropical countries. It is the most important food-pro- 

 ducing species of the Family. Its native country is uncertain, 

 but evidence favours its American origin. Many of the 

 Bindweeds are useful in medicine. A Mexican species 

 {Exogomtmi Furga) affords the drug Jalap, and a Convolvtthis 

 of the Levant (C Scainmofiid) Scammony. 



The Dodders {Ctiscutce) constitute a remarkable Sub- 

 type of this Family. They are twining, leafless, parasitical 

 herbSj with small white corollas, often with minute scales 

 inside, al^rnating with the stamens. Their embryo is 

 spirally twisted, and is usually destitute of cotyledons. It 

 germinates independently in the soil, but as early as possible 

 lays hold of some neighbouring plant, to which it attaches 

 itself by small suckers given off by its stem. One species, 

 C. 7'efiexa^ is common in India. 



66. Natural Order, BoraginacecB. — The Borage Family. 



Herbs, shrubs, or rarely trees, with alternate, simple, 

 often rough leaves, and unilateral cymose inflorescence. 

 Flowers regular, with stamens alternate with corolla-lobes 

 Ovary, four- (rarely two-) lobed, four- (two-) seeded. 



