176 The Natural System of Botany. 



Order — CruciferjE. The Cruciferous Tribe. 



This is a very large and important order, comprehendin 

 nearly nine hundred species, among which are many of th 

 most useful and ornamental plants. The Turnip, CaulinW er 

 Cabbage, Mustard, Cress, Radish, are universally cultivated 

 as edible vegetables, and the Wall flower, and Slock gilliflower 

 as showy garden flowers. They all possess a peculiar acrid 

 stimulating principle, dispersed throughout every part, often 

 accompanied with an etherial oil. Their flowers are generally 

 small, but marked with such obvious characters that they can 

 hardly be mistaken. One of these characters is the number 

 and arrangement of the stamens, which is scarcely subject to 

 the least variation, and which is peculiar to this order. The 

 number of stamens is six, of which two are shorter than the 

 rest, corresponding to the most natural of the Linnaean classes 

 Tetradynamia. Their arrangement, as well as that of the 

 petals, is somewhat in the form of a cross, from which the 

 name of the order is derived, the four long stamens being 

 placed above and below, and the two shorter at the sides. 

 There is a very common little weed, known to every body 

 under the name of Shepherd's Purse, (Capsella bursa-pastor'u) 

 which grows by every roadside, producing its minute white 

 flowers all summer. Its name seems to have been given it 

 from its seed vessel having small pockets, with minute flat 

 seeds, like fairy coins. Let the student procure a specimen 

 of this, and examine its construction. The flowers are 

 arranged in a raceme, and are quite destitute of bracts, the 

 absence of which is a mark of this tribe. Observe, I pray vou, 

 says Lindley, how very useful it is to be aware of this. Ima- 

 gine yourself cast away upon a desert island ; and there, sur- 

 rounded with plants of unknown forms and tempting looks, 

 none of which you dare use from fear of their proving poison- 

 ous. Among them, however, you remark a good many of the 

 same kind, one of which is just beginning to bear its tufts of 

 flowers : the blossoms are too young to be examined, but old 

 enough to show you that they grow without bracts ; the leaves 

 you would easily see were those of Exogenous plants, and you 



