560 MONOECIA. 



understood, and, having frequently united flowers, 

 belongs to the second Class ; see Engl. Bot. t. 926, 

 1095, 1233. 



3. Triandria. The great genus of Carex, t. 1051, 

 928, 993 995, &c., and some other grassy plants, 

 are found here. Typha, t. 14551457, is less 

 clear in its structure ; Sparganium, t. 744, 745, 

 273, is sufficiently so. Tragia, Hernandia and 

 Phyllanthus are properly placed in this Class and 

 Order. 



4. Tetrandria. Littorella, t. 468 ; the valuable genera 

 Betula, t. 1508, and Buxus, t. 1341 ; also the 

 Nettle Urtica, t. 1236; are good examples of this. 

 Morus the Mulberry, of the same natural order as 

 the Nettle, has scarcely any difference of structure 

 in the accessory organs of the flowers. This tree, 

 however, is remarkable for being often inclined to 

 become even dioecious in its constitution, one indi- 

 vidual bearing most fruit when accompanied by an- 

 other whose barren flowers are more effective than 

 its own. Empleuruniy Exot. Bot. t. 63, is one of 

 those ambiguous genera which are but imperfectly 

 monoecious. 



5. Pentandria. Xattthium, Ambrosia, Nephdium, 

 Parthenium, Iva and Clibadium all partake, more 

 or less accurately, of the nature of compound 

 flowers ; but their anthers not being united, they 



