TETRADYNAMIA. 531 



2. Angiospermia. Seeds in a capsule, and generally 

 very numerous. — The plants of this order have the 

 greatest possible affinity with some families in Pen- 

 tandria Monogynia. Some species even vary from 

 one class to the other, as Bignonia i^acUcans, Curt, 

 Mag. t. 485, and Antirrhinum Linaria., Engl. Bot. 

 t. 658, 260, in which the irregular corolla becomes 

 regular, and the four unequal stamens are changed 

 to five equal ones ; nor does this depend, as has 

 been asserted, on the action of any extraneous pollen 

 upon the stigmas of the parent plant, neither are 

 the se^ds always abortive. No method of arrange- 

 ment, natural or artificial, could provide against such 

 anomalies as these, and therefore imperfections must 

 be expected in every system. 



Class 15. Tetradijnamia. Stamens4longand2short. 

 Orders 2, perfectly natural. Flowers cruciform. 



1. Siliculosa. Fruit a roundish pod, or pouch. In 

 some genera it is entire, as Drabci, Engl. Bot. 

 t. 586, and the Honesty or Satin flower, Lunaria : 

 in others notched, as Thlaspi, t. 1659, and Iberis, 

 t. 52 ; which last genus is unique* in its natural 

 order in having unequal petals. Crambe, t. 924 ; 

 Isatisj t. 97; and Bunias, /, 23 1 ; certainly belong to 

 •this Order, though placed by Linnseus in the next. 



2. Siliquosa. Fruit a very long pod. Some genera 

 have a caly.v clausus, its leaves slightly cohering by 



* Except one species of Teesdalla, Sm. Compend, ed. 3. 98. 



