ORDER SILICULOSA. 137 



very truly, to be transverse, or as it were in an opposite 

 direction to that of the dissepiment in the silicle. One 

 of the most remarkable examples, though deviations 

 from the ordinary character of the capsella or silicle, 

 is that of the Psychine, so named from Psyche, the 

 Butterfly, in allusion to the fruit which instead of 2, pre- 

 sents constantly 3 cells, and 3 broadly carinated valves, 

 to the silicle. The same number of valves, though not 

 constant, may often be observed in the fruit of the com- 

 mon Candytuft (Iberis umbellata). In Biscutella, 

 the dissepiment is reduced to a mere axis of attach- 

 ment, to apparently, 2 different circular flat silicles, 

 united as one fruit by their edges merely, and hence 

 the name, which signifies 2 little shields. 



One of the most common weeds of this order, 

 though worthy of examination, is the Shepherd's-purse 

 (T/ilaspi Bursa-pastoris)', deriving this specific name 

 from the peculiar form of the capsule. The plant has 

 but little to recommend it, being an unsightly annual, 

 running, only too quickly, over neglected gardens and 

 wastes, and is one of those plants, like the Chickweed, 

 and the Black Nightshade (Solnum nigrum), which 

 have made themselves denizens of the whole habitable 

 world. In the United States it is quite common on 

 the banks of the Mississippi, and the more distant 

 Missouri. Its radical leaves are pinnatifid, with the 

 divisions toothed, and sometimes bent in an arch. 

 The flowers are very small and white. The silicle or 

 capsella, which gave name to the plant itself amongst 

 the ancient botanists, is triangularly obcordate, but 

 without a keel or empty margin ; and the cells, each, 

 contain a multiplicity of minute seeds. Such ought 

 to be the description of the genus, which would then 

 probably include no other plant ; but at present, by 

 many, the genus is very unphilosophically constructed, 

 so as, in reality, to exclude our Shepherd's-purse, and 

 12* 



