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) : while 

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

 weigh forty or fifty pounds, are farinaceous, with 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. Sllboi'd. Dichondreffi. Ovaries two to four, either entirely 

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

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

 Ex. Dichondra. 



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

 by circumcissile dehiscence, or bursting irregularly. Embryo fili- 

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



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

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



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

 cf the natural size 1043. A flower, enlarged. 1044. The same, laid open. l'!45 Section of 

 the ova y. 1046 Section of the capsule aud seeds. 1047. The spiral embryo detached. 1048. 

 The same in germination. 



