288 WEED FLORA OF IOWA 



Distribution. — Buffalo bur is originally native of the plains 

 region, between the Missouri river and the Rocky mountains. It 

 has spread eastward in the northern states and extensively in 

 Texas, Mississippi and Arkansas. It is not infrequent from 

 Tennessee to New York. It has been found in Germany. This 

 weed is widely scattered in small patches in many parts of the 

 state of Iowa. 



Extermination. — Inasmuch as this weed is an annual, it can be 

 easily exterminated by cutting off the young plants below the 

 ground and this should be done before the pods are formed. If 

 plants are older they should be cut off and burned. 



The Iowa Homestead says concerning this weed: "On account 

 of the fact that the buffalo bur is an annual its destruction or 

 eradication is simply a matter of preventing it from maturing its 

 seed. Corn fields that are badly infested may need but little at- 

 tention after the regular time for laying the corn by, for which 

 purpose the one horse cultivator may be pressed into use." 



Dr. C. E. Bessey in Breeder's Gazette recommends as follows: 

 "To get rid of it the best thing is first not to allow the weed to 

 get a good start, as its deep roots are hard to get out. Second, if it 

 has a good start, the plants must be cut down frequently so as to 

 prevent their seeding and thus starting new plants. In the third 

 place, the deep roots must be killed by digging out or by smother- 

 ing. This can be done by using a very heavy dense crop like some 

 of the sorghums, or by covering the patch with wet manure. Of 

 course constant stirring of the soil will kill them. It will pay to 

 watch this weed wherever it appears." 



Purple Thorn-apple, Purple Stramonium, or Jimson Weed 

 (Datura tatula L.). 



Description. — A glabrous annual from a few inches to 5 feet 

 high; stem purplish; leaves thin, ovate, acute or acuminate; flowers 

 consisting of a 5-toothed calyx and a 5-lobed funnel form corolla, 

 with stamens included ; filiform filaments inserted below the mid- 

 dle of -the corolla tube; capsule globular, prickly, 4-valved and 

 2-celled. The common thorn-apple (Datura stramonium) is a glab- 

 rous annual with green stem, sinuate-toothed leaves and white 

 corolla. 



