178 



WEEDS AND USEFUL PLANTS. 



Obs. Tms worthless weed occurs in most cultivated grounds, and is 

 usually very abundant among the stubble, after a crop of wheat : but, 

 if the land be good, the plant seems te be smothered or choked out, the 

 next season, by the crop of clover and timothy. It is always ready, 

 however like several other coarse weeds to make its appearance 

 whenever the grassy turf is broken up. The curious anomaly above 

 mentioned, of the flowers on the terminal spikes being all pistillate, 

 is frequently met with. 



9. XAN'THIUM, Tournef. CLOT-BUR. 



[Greek, JTanthos, yellow ; a color said to be produced by the plant.]- 



Heads monoecious, in spicate clusters the sterile spikes at the summit. 



321 



120 



FIG. 119. Flowering .summit of the Cockle-bur (Xanthium strumarium), with heads of 

 staminate flowers above, the pistillate ones below. 120. A separate staminate flower very 

 much enlarged. 121. A head of (2) pistillate flowers enclosed in the prickly involucre. 



