116 



Descriptive Flora 



the objectionable burs and spiny seeds are causing much havoc 

 among the motorists of those regions. The possibilities for dam- 

 age from this plant are well illustrated by the experiences of a 

 California motorist who reported 70 punctures in one tire, all 

 due to the puncture vine. In some sections where the puncture 

 plant has become established, one-half of the bicycle tire and 

 approximately one-quarter of the automobile tire punctures re- 

 sult from the spiny burs of this plant which are distributed 

 along the waysides. 



Fortunately, the puncture plant is an annual and on tillable 

 ground, it can be controlled by repeated cultivation which pre- 

 vents the formation of seed. Along the roadsides, where the 

 weeds are most dangerous from the standpoint of the motorists, 

 mowing has been resorted to unsuccessfully as an eradication 

 expedient. The vines grow so low and spread so close to the 

 ground that it is impossible to cut them off satisfactorily with 

 the mower before they form seed. Furthermore, many of the 

 plants which are clipped will subsequently produce burs and 

 seed the same season. The national agricultural authorities are 

 now testing out the effectiveness of iron sulfate and crude oil 

 sprays for destroying the puncture plant. Potentially, they ex- 

 pect to perfect control measures which will mimimize the motor- 

 ing dangers due to the puncture plant, the unwelcome emigrant 

 which reached our shores by stowaway methods.' 9 



Kalstroemia Jiirsutissima Vail. Caltrop 



Hairy plants, with stout, radially-spreading, prostrate 

 branches, orange-colored, 5-petaled flowers and pinnately com- 

 pound leaves of 6 to 10, unequally-sided leaflets. Flowers about 

 y% across, singly terminating axillary peduncles % to 1" long. 

 Petals 5, orange. Stamens 10, 5 long, 5 short. Sepals 5, narrow, 

 hairy. Pod globose, about y± across, with 10-12 rough, warty 

 angles, and a thick stout beak as long as the body. Sepals per- 

 sistent. April to fall. Common weed. Differs from Tribulus 

 terrestris in the larger and fewer number of leaflets, the deep 



