CRUCIFER.E, OR TURNIP TRIBE. 367 



of laudanum is as much as it is usually safe to give, the dose for 

 an adult being twenty times as much. 



528. All the Papaveraceae belong to the Linnsean Class 

 POLYANDRIA, and to the order Monogynia; the style being 

 apparently single, though formed by the union of many. 



Order CRUCIFER^E, or Turnip Tribe. 



529. This order is one of the most important to Man, in 

 respect to the amount of wholesome food which he directly or 

 indirectly derives from it, of the entire group of Exogens. It 

 comprehends the Turnip, Cabbage, Sea Kale, Mustard, Cress, 

 Radish, and other edible Vegetables ; as well as the Rape, culti- 

 vated for the oil yielded by its seed; and Stocks and "Wall- 

 flowers, valued as showy garden-plants. As the flowers are 

 generally small, there might be some difficulty in recognising 

 them ; were it not that they are marked by very obvious cha- 

 racters, which are easily observed, and can scarcely be mistaken. 

 One of these characters is derived from the number and arrange- 

 ment of the stamens ; which throughout the whole of this order 

 are scarcely subject to variation, and which are not presented by 

 any plants that do not belong to it. The number of stamens is 

 six ; but four of these are longer than the rest ; so that they 

 would be characterised in Linnaean classification as tetradynamous 

 (. 483) ; and in fact the Linnsean class TETRADYNAMIA, and this 



order Crudfera, correspond precisely. The arrange- 

 ment of these stamens, somewhat in the form of a 

 6 Maltese cross, is another peculiarity, from which the 

 name of the order is derived ; the four long stamens 

 are placed above and below, and the two shorter ones 

 at the sides. Some other less constant characters will 

 be noticed as we proceed. 



530. A good example of this Order will be found in a com- 

 mon weed, named Shepherd^ Purse (Capsella Bursa pastoris), 

 which may be found almost everywhere, and at all but the coldest 

 seasons of the year. Its name seems to have been derived 



