10 



WEED FLORA OF IOWA 



nerved and usually silky-villous along the marginal nerves, fourth 

 glume smooth and acute; fruit minute, pitted and cross-striated, 

 light straw color except where the sterile glumes remain attached, 

 which are gray in color and minutely hairy. 



Distribution. — This European grass is cosmopolitan ; abundant in 

 the eastern and southern states and in California; common in all 

 parts of Iowa, more particularly in gardens, corn fields, and streets. 



Extermination. — This grass is much more difficult to remove than 

 the foxtails because it roots so readily at the joints. Thorough 

 cultivation will remove the weed. Do not allow it to go to seed. 



Chemical Composition. — Common crab grass (Digitaria sanguin- 

 alis) has been used as a forage plant in many parts of the United 

 States and many chemical analyses have been made. Analyses are 

 reported from Mississippi, Tennessee and Iowa. The Iowa analysis 

 reported by Weems is as follows : 



NATURAL CONDITION 



Smooth Crab Grass (Digitaria humifusa Pers.) . 



Description. — An annual 6 in. -2 ft. high, closely resembling D. 

 sanguinalis in habit, but smooth throughout, excepting for a few 

 hairs at the throat of the sheaths ; spikelets 2-7, smaller than in 

 D. sanguinalis, about 1 line in length; first glume very minute or 

 obsolete; second and third glumes nearly equal in length, or the 

 second a little shorter than the fourth, pubescent at the back. 



Distribution. — Smooth crab grass is native to Europe but is 

 now cosmopolitan ; in eastern North America from New England 

 to Texas and Mexico, Rocky mountains and Pacific coast ; less com- 

 mon in Iowa than common crab grass; rapidly spreading in the 

 state, more particularly in gardens ; common in lawns and pas- 

 tures. 



