EXOGENOUS OR DICOTYLEDONOUS PLANTS. 



455^ 



chiefly found in their thickened or tuberous roots. Convolvulus 

 Jalapa, and other Mexican species, furnish the Jalap of the shops. 

 The more drastic Scammony is derived from the roots of C. Scam- 

 monia of the Levant. There is much less of this in those of Con- 

 volvulus panduratus (Man-of-the-Earth, "Wild Potato-vine) : Avhile 

 those of C. macrorhizus of the Soutliern States, which sometimes 

 weigh forty or fifty pounds, are farinaceous, Avith so slight an ad- 

 mixture of this matter as to be quite inert ; as is also the case with 

 the Batatas, or Sweet Potato, an important article of food. — To this 

 family are appended, as tribes or suborders, 



882. Subord. Diclionilreit. Ovaries two to four, either entirely 

 distinct or Avith their basilar styles more or less united in pairs. 

 Creeping plants, with axillary, scape-hke, one-flowered peduncles. — 

 Ex. Dichondra. 



883. Subord. CusCUtineac. Ovary two-celled ; the capsule opening 

 by circumcissile dehiscence, or bursting irregularly. Embryo fili- 

 form, and spirally coiled in fleshy albumen, destitute of cotyledons ! 



1043 



1042 



1047 



1048 



lOlS 



1046 



Parasitic, leafless, twining herbs, destitute of green color. Stamens 

 usually furnished with fringed scales within. — Ex. Cuscuta (Dodder). 



FIG. 1042. A piece of Cuscuta Gronovii, the common Dodder of the Northern United States, 

 of the natural size. 10i3. A flower, enlarged. 1044. The same, laid open. 1045. Section of 

 the ovary. 1046. Section of the capsule and seeds. 1047. The spiral embryo detached. 1048. 

 The same in germination. 



