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 
Pande Fie. 182. — Alfilaria or Filaree 
Tribulus terréstris, L. (Erodium cicutarium). X }. 
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 
