ZYGOPHYLLACEAE (CALTROP FAMILY) 



259 



a larger, coarser plant, with less 

 finely divided leaves and some- 

 what larger flowers. Less valuable 

 as a forage plant, for cattle do not 

 relish its musky odor and taste ; 

 sheep, however, do not seem to 

 object to it. Both plants invade 

 grain fields to the disadvantage 

 of the crop. 



Means of control 



Prevent seed production. Put 

 the ground under cultivation in 

 order to stir dormant seeds into 

 germination, and give such fre- 

 quent tillage that no seedlings will 

 be allowed to mature. 



GROUND BUR-NUT 

 Tribulus terrestris, L. 



FIG. 182. Alfilaria or Filaree 

 (Erodium cicutarium). X J. 



Other English name: Land Caltrop. 



Introduced. Annual. Propagates by seeds. 



Time of bloom: June to August. 



Seed-time: July to September. 



Range : Iowa, Illinois, Kansas, and Nebraska ; also about Atlantic 



seaports. 

 Habitat: Pastures, waste places. 



The Caltrop is native to the Mediterranean regions of Europe, 

 and is said to have been brought into its western range in the 

 fleeces worn by imported sheep ; and it is a very troublesome weed 

 to wool-growers. 



Stems eight inches to nearly three feet long, branching from the 

 base, and often forking above, weak, slender, silky-hairy, some 

 prostrate and others ascending, spreading on all sides. Leaves 

 numerous, also silky-hairy, evenly pinnate, short-petioled, with 

 ten to fourteen small, oblong, sessile leaflets, the pairs frequently 

 unequal in size. Flowers axillary, on peduncles shorter than the 



