in the West, with broom snakeweed the most common and abundant. It is 

 widely distributed over the Western States, ranging from Alberta to Manitoba, 

 western Texas, southern California, Nevada, and Idaho. It occurs principally 

 on the plains, in semidesert valleys, on low-lying foothills and mountain slopes, 

 at from 4,000 to 8,000 feet above sea level. This species is frequently abun- 

 dant and conspicuous on desert ranges of the Intennountain Region, in asso- 

 ciation with shadscale, black sagebrush, dropseeds, gramas, and Indian rice- 

 grass. On the foothills and in the juniper-pmon typo, it is commonly associated 

 with big sagebrush, rabbitbrushes, and downy chess ; on the plains of western 

 Kansas and Nebraska it is frequently found among gramas and buffalo grass; 

 and in the Southwest it is common in the oak type and also on lower ranges, 

 intermixed with mesquite and soapweed. 



Broom snakeweed commonly inhabits dry, well-drained, sandy, gravelly, or 

 clayey loams, but is able to grow on adobe and other heavy clay soils. It 

 flourishes best on the moderately rich limestone clay loams of broad alluvial 

 slopes, but also thrives on shallow, rocky, or sandy soils. It apparently does 

 not occur on saline or alkaline soils. 



Throughout most of its range this plant is considered worthless as forage. 

 However, on the winter ranges, notably in western Utah and eastern Nevada, it 

 ranks as fair forage for sheep but poor for horses and cattle during the fall 

 and spring. Horses eat the plant during the winter, while sheep utilize it 

 most directly after growth begins in the spring, presumably because it is one of 

 the first to begin growth, sending out small green shoots at the base of the 

 old dry stems of the previous season. Sheep often relish this young succulent 

 foliage, but usually discard the dry, unpalatable stems. Such usage is un- 

 questionably enhanced by the paucity of better, more palatable forages, which 

 are particularly scarce early in the grazing season. 



Broom snakeweed is a very aggressive plant, which rapidly invades areas 

 where the climax vegetation has been depleted by fire, grazing, or drought. 

 On many of the depleted semidesert ranges of western Utah and eastern Nevada, 

 this plant frequently abounds over considerable areas. It occurs with downy 

 chess on burnt-over big sagebrush areas in the Great Salt Lake district of 

 Utah. 1 In eastern Colorado it rapidly invades depleted grama and buffalo grass 

 ranges ; in the Southwest, it is an excellent indicator of range deterioration, 

 being one of the first plants to invade ranges where the better forage grasses 

 have been decimated or destroyed by overgrazing. 2 



Although this species is unimportant as forage, being grazed chiefly, if 

 not entirely, for lack of something better, it plays a definitely important role 

 on ranges depleted of better vegetation in protecting the soil against wind 

 and water erosion. 3 Wholesale depletion of the more palatable species, without 

 the invasion of replacements, would result in very serious soil losses. However, 

 this species is a much less valuable soil cover than many of the grasses, 

 as recent studies of the Southwestern Forest and Range Experiment Station 

 show that surface run-off and soil loss are much greater on partially depleted 

 grama ranges invaded by broom snakeweed than on areas where the original 

 grass cover still exists. 



Heavy utilization of this plant by livestock probably results in sickness 

 or death, as reported by the late Dr. C. D. Marsh, and by stockmen, 4 but the 

 plant is, without question, frequently grazed by domestic animals without 

 ill effects. 



Broom snakeweed is often preyecl upon and killed by certain borers and 

 insects, such as species of Crossidius, Diplotaxis, Mecas, and Aphis* Several 

 species of aphids have been reported as feeding upon broom snakeweed in 

 Utah. 6 This has encouraged the hope that, through them or other agencies, 

 snakeweed may eventully be eradicated from areas where it is now a pest. 



1 Pickford, G. D. THE INFLUENCE OF CONTINUED HEAVY GRAZING AND OF PROMISCUOUS 



BURNING ON SPKING-FALL RANGES IN UTAH. Ecology 13 : 159-171, illUS. 1932. 



2 Jardine, J. T.. and Forsling, C. L. RANGE AND CATTLE MANAGEMENT DURING DROUGHT 

 U. S. Dept. Agr. Bull. 1031, 84 pp., illus. 1922. 



8 Campbell, R. S., and Bomberger, E. H. THE OCCURRENCE OF GUTIERREZIA SAROTHRAE 



ON BOUTELOUA ERIOPODA RANGES IN SOUTHERN NEW MEXICO. Ecology 15 (1) : 49-61. illltS. 



1934. 



4 Dayton, W. A. IMPORTANT WESTERN BROWSE PLANTS. U. S. Dept. Agr. Misc. Pub. 

 101, 214 pp., illus. 1931. 



6 Pack, H. J., and Knowlton, G. F. A FEW MATCH BRUSH APHIDS FROM UTAH. Canad. 

 Ent. 61: 199-204, illus. 1929. 



