474 JdONOECIA. 



3. Triandria. The great genus of Carex, 

 t. 1051, 928, 993—995, &c, and some 

 other grassy plants, are found here. Typha, 

 t. 1455 — 1457, is less clear in its struc- 

 ture; Sparganium, t. 744, 745, 273, is 

 sufficiently so. Tragia, Hernandia and 

 Phyllantfius are properly placed in this 

 Class and Order. 



4. Tetrandria. Littorella, t. 468 ; the valua- 

 ble genera Betula, t. 1508, and Bmus, 

 L 1341; also ; the Nettle Urtica, U 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 individual 

 bearing most fruit when accompanied by 

 another whose barren flowers are more ef- 

 fective than its own. Emplcurnm, ExoU 

 Bot. t. 63, is one of those ambiguous ge- 

 nera which are but imperfectly monoe* 

 cious. 



