350 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



3. Sisymbrium linifolium Nutt. ex Torr. and Gray, Fl. North Amer. 1: 



91. 1838. 



Nasturtium linifolium Nutt., Acad. Nat. Sci. Phila. Jour. 7: 



12. 1834. 

 Schoenocrambe linifolia Greene, Pittonia 3: 127. 1896. 



Carrizo Mountains, Apache County, possibly collected on the New 

 Mexico side of the State line (Matthews in 1892), western slope of the 

 Kaibab Plateau (Goodding and Gunning 2959). Montana to British 

 Columbia, Utah, and northern Arizona. 



4. Sisymbrium irio L., Sp. PL 659. 1753. 



Norta irio Britton in Britton and Brown, Illus. Fl. ed. 2, 2: 174. 

 1913. 



Maricopa, Pinal, Santa Cruz, Pima, and Yuma Counties, 4,500 feet 

 and lower, winter and early spring. Introduced from Europe. 



An extremely abundant weed in irrigated sections of southern 

 Arizona, disappearing on the advent of hot weather, of possible value 

 for green manure. 



5. Sisymbrium altissimum L., Sp. PL 659. 1753. 



Norta altissima Britton in Britton and Brown, Illus. Fl. ed. 2, 2: 

 174. 1913. 



Coconino, Mohave, and Yavapai Counties, a common roadside 

 weed, 5,000 to 6,500 feet, occasional farther south and lower, May to 

 July. Introduced from Europe. 



Tumblemustard. A bad weed in grainfields in some parts of the 

 United States. 



Sisymbrium officinale (L.) Scop., an introduced weed common throughout most of 

 the United States, is to be looked for in Arizona. 



13. HALIMOLOBUS 



Plant perennial, soft-canescent, with mostly forked or stellate hairs; 

 stems diffusely branched above; leaf blades deeply sinuate or pin- 

 natifid; petals bright white; pods terete, very slender, less than 1 mm. 

 in diameter. 



1. Halimolobus diffusus (A. Gray) O. E. Schulz, Pflanzenreich IV. 

 105: 288. 1924. 



Sisymbrium dijfusum A. Gray, PL Wright. 1: 8. 1852. 



Pine Creek, Gila County (MacDougal in 1891), Mule Mountains, 

 Cochise County {Goodding 971), Baboquivari Mountains, Pima 

 County, about 4,000 feet (Peebles et al. 2777), mostly in crevices of 

 rocks, July and August, apparently rare in Arizona. Western Texas 

 to southern California and northern Mexico. 



14. MICROSISYMBRIUM 



Plant annual or biennial, sparsely pubescent below with simple 

 hairs; leaves coarsely pinnately cleft; petals whitish, narrow, less 

 than 5 mm. long; pods elongate, terete. 





