48 



WEEDS AND USEFUL PLANTS. 



Ohs. This is an exceedingly troublesome weed in Europe, and is be^ 

 coming so in some portions of this country. It infests those grounds 

 which are best suited to grain-culture ; as the seeds retain their vitality 

 for a long time it is very difficult to eradicate it when once established. 



In this, as in other cases, the plant should be destroyed before the seed 

 is formed ; as sheep are fond of the herbage they are sometimes turned 

 into a field to destroy the crop of Charlock. 



Pod (pouch) elliptical or globose ; the valves turgid, not nerved. 

 Petals white, much longer than the calyx. Seeds numerous. Leaves 

 undivided or the lower ones pinnatifid. 



1. A. rv,stica'na,Rupp. Eadical leaves on long petioles, oblong, crenate, 

 rarely pinnatifid ; those of the stem lanceolate. 

 Rustic i^RMORACiA. Horseradish. 



Fr. Moutarde des Capucins. Germ. Der Meer-Eettig. Span. Eabano. 



Root perennial, long, terete, fleshy white, very acrid. Stefm 2-3 feet hi^h, angular- 

 striate, smooth, with erect axillary branches. Radical leaves large (8-15 inches long — 

 somewhat resembling those of a Dock, or Rumex) ; petioles A -12 inches long. Racemes 

 corymbose, elongating. PetoZ^ white. Silicles oval, usually abortive. 



Gardens : margins of ditches, &c. : introduced. Native of Europe. Fl. May- June. 

 Fr. June -July. 



Fig. 21. Field Mustard (Sinapis arvensis) , illustrating the general appearance of flowers 

 in this family, 22. An enlarged flower opened to show the unequal stamens. 23. A pod, 



6. ARMOR A' CIA, Rupp. Horsekadish. 



[Name from one of the Greek names for Radish.] 



