742 MISC. PUBLICATION 423, U. S. DEPT. OF AGRICULTURE 



especially in rocky calcareous soil. Texas to southeastern California 

 and Mexico. 



The distribution in Arizona as stated above is that of the typical 

 form, with corollas 5 to 8 mm. long, 4 to 6 mm. wide. In the Castle 

 Dome, Kofa, and Plomosa Mountains (Yuma County) there occurs 

 var. pulchella Johnston, with corollas much larger (9 to 12 mm. long, 

 5 to 8 mm. wide) and apparently more deeply colored, type from the 

 Kofa Mountains (Shreve 6257). This variety is poorly understood, 

 and field observations are needed before its exact relationship to 

 typical C. canescens can be established. This species is useful for 

 controlling soil erosion. 



2. Coldenia hispidissima (Torr.) A. Gray, Amer. Acad. Arts and Sci. 



Proc. 5: 340. 1862. 



Eddya hispidissima Torr., U. S. Rpt. Expl. Miss. Pacif. 2: 170. 

 1855. 



Basin of the Colorado River and its tributaries, south to near Hol- 

 brook, and west to Beaver Dam, 2,000 to 5,000 feet, dunes and dry 

 open slopes. Southern Utah, Nevada, and northern Arizona. 



The Arizona form is var. latior Johnston, with broader, more lance- 

 olate leaves than in the typical form of the species. 



3. Coldenia nuttallii Hook., Jour. Bot. and Kew Gard. Misc. 3: 296. 



1851. 

 Northern Arizona (Virgin River, Painted Desert) in dry sandy 

 places. Wyoming to Washington, Arizona, and California; Ar- 

 gentina. 



4. Coldenia plicata (Torr.) Coville, Contrib. U. S. Natl. Herbarium 4: 



163. 1893. 



Tiquiliabrevijolia plicata Torr., U. S. andMex. Bound. Bot. 136. 



1859. 

 Coldenia palmeri of S. Wats, and recent authors. Not of A. Gray, 



1870. 



Extreme western Arizona and eastward along the Gila and Salt 

 Rivers to Sacaton and Tempe, mostly below 1,500 feet, sandy flats 

 and dry river bottoms. Deserts of the Larrea belt, southern Nevada 

 and southeastern California to northwestern Mexico. 



5. Coldenia palmeri A. Gray, Amer. Acad. Arts and Sci. Proc. 8: 292. 



1870. 



Coldenia brevicalyx S. Wats., ibid. 24: 62. 1889. 



At Topock and Fort Mohave (Mohave County) , Yuma and Wellton 

 (Yuma County), 500 feet or lower, dry sandy places in the Larrea belt. 

 Extreme western Arizona, southeastern California, and adjacent 

 Mexico. 



2. HELIOTROPIUM. Helioteope 



Herbs; flowers in scorpioid cymes or borne along the stem usually 

 between or opposite the leaves; corolla white; fruit unlobed, at matu- 

 rity breaking up into 4 nutlets or f ailing away entire. 



