220 NATURAL HISTORY OF PLANTS. 



Papaveracece, and link it so well with Manunculacece. But it is 

 undoubted that Cruciferce come next to Papaveracece on the one hand 

 and CapparidacetB and Mesedacece on the other; so that if the sum total 

 of natural affinities be considered they must be placed between these 

 three orders. They differ from all of them in the distinctly cruciform 

 perianth and generally definite tetradynamous anthers, no less than in 

 the structure of the fruit and seed, To distinguish the tetradynamous 

 Capparidacea with dry dicarpellary fruit, the only characters are the 

 unsymmetrical flowers, the habit, the 1-3-foliolate leaves, and 

 the absence of a false septum in the fruit. Mesedacece are separated 

 by their indefinite unilateral androceum and the structure of their 

 fruit. Certain types of Papaveracece approach so close to Cruciferce 

 that they can only be distinguished by their indefinite androceum 

 {Fumariea? are an exception to this), when their fruit becomes dicar- 

 pellaiy, very much like a siliqua, and with a false septum compar- 

 able to that of a Crucifer. Then the only difference lies in the t}^pe 

 of the flowers, quaternary in this order, but ternary in Papaverads 

 or repeatedly binary with a double or triple corolla of dimerous 

 verticils, not of a single tetramerous whorl. Finally the embiyo of 

 Papaveracece is always accompanied by an albumen much larger 

 than itself. 



The geographical distribution of this order would alone 

 suffice for a great work. Of one hundred and sixty-three genera 

 retained by us in this order, twenty-two are confined to America ; 

 seventeen are common to both Worlds, and a hundred and 

 twenty-four are only found in the Old World. Of the species 

 some authors have raised the number to upwards of two thousand : 

 we admit some thirteen hundred, whereof six hundred and seventy 

 belong to the Old World genera, and eight} T -four to the 

 American ; of the remaining five hundred and forty T -seven, be- 

 longing to the genera common to both Worlds, not more than a 

 tenth part are American, so that the sum total of the species in the 

 New World is about one hundred and forty against some eleven 

 hundred and sixty in the Old. Next comes the question of latitude. 



Bernh., in Linnaa, viii. 401 ; in Ann. Sc. JS'at., Teg. Kingd., 351. — J. G. AGAEDH., Theor. Syst. 

 ser. 2, iii. 357.— J. Gay, in Ann. Sc. Nat., ser. PL, 212. 

 2, xviii. 218. — Endl., Enchirid., 452. — Lindl., 



