MONOCOTYLEDONS AND DICOTYLEDONS 



243 



is often hard. Usually a perianth is present, but with no 

 differentiation of calyx and corolla, and the flower parts are 

 quite definitely in " threes," so that the cyclic arrangement 

 with the characteristic Monocotyledon number appears. 



Fig. 224. A fan palm, with low stem and crown of large palmate leaves, w hich hav( 

 split 80 as to appear palmately branched. —From •• Plant Relations." 



134. Aroids. — This is a group of nearly one thousand 

 species, most of them belonging to the family AracecB. In 

 our flora the Indian turnip or Jack-in-the-pulpit {Aris(P7na) 

 (Fig. 225), sweetflag (Acorus), and skunk-cabbage (Sijinplo- 

 carpus), may be taken as representatives ; while the culti- 

 vated Calla-lily is perhaps even better known. The great 

 display of aroids, however, is in the tropics, where they are 

 endlessly modified in form and structure, and are erect, or 

 climbing, or epiphytic. 



