TAXONOMY 



387 



woody, perennial climbing plants with underground parts sometimes 

 swollen into tuberous roots (Jalap, Sweet Potato, Wild Man of the 

 Earth). Stems rarely short, upright or tufted, usually elongate 

 and circumnutating in action. Vascular bundles frequently bi- 

 collateral. Leaves alternate, simple, exstipulate, varying from 



FIG. 226. Convolvulus scammonia Branch. (Sayre.) 



cordate to cordate-sagittal, to broad reniform to reniform, palmately 

 lobed to palmatifid to palmately-compound (Ipomaa shows all these 

 transitions). Stem and leaves frequently contain a dull, viscous, 

 watery to milky-white juice. Inflorescence a scorpioid cyme be- 

 coming reduced in some forms to a solitary flower. Flowers penta- 



