EUPHORBIACEAE 



inconspicuous flowers. It is abundant in extreme southern Hew 

 Mexico, southern Arizona, southern California and Hexico, in low 

 rocky foothills where the temperature in the summer becomes very 

 high. Though it is a good erosion control plant where it grows 

 naturally, it probably is not well adapted to nursery practices 

 and its range is very limited. Its forage value is low* 



Pi ta x is s ericophylla is a low shrub with narrow gray, silky 

 leaves and similar gray silky stems. It grows only in the extremely 

 dry, hot low ranges of southwestern Arizona and adjacent Sonora. 

 As an erosion control plant it can never be considered unless reve- 

 getation work is undertaken in these extreme desert sections. It 

 is an erosion control plant and is relished, by mountain sheep. 



Acalypha pr inglei is a very tender shrub confined to Pima 

 and Yuma counties in Arizona and adjacent Hexico in extremely dry 

 situations. In the nursery at Tucson it makes a handsome shrub 

 but without protection freezes to the ground in the winter. It 

 is suitable only for an ornamental at present but at such time as 

 our work is extended into the Phoenix and Yuma regions it may have 

 its place. 



Sapium bil ocu lar e is abundant in southern Pima County, Arizona 

 and is widely distributed in Hexico. It is a tall shrub with nar- 

 row leaves and milky juice which has been used medicinally for 

 probably hundreds of years. It is visciously poisonous. The leaves 

 are used by the Indians for stupefying fish. The milky juice 

 gotten into the eyes even in the minutest quantity, as by rubbing 

 the eyes after handling the plant, causes extreme pain for hours. 

 It is not improbable that this plant will be found to have commer- 

 cial importance when its latex is studied carefully. 



Ricinus communis, or 'Castor Bean, is an introduction into 

 all the warmer portions of the United States. In many places it 

 is raised as an annual ornamental because of its rapid growth and 

 showy leaves and flowers. Attempts have been made to raise it 

 commercially in this country but without success, probably because 

 of high cost of labor here. It is unsuited for use for anything 

 except an ornamental. 



Manihot angu stilo ba may be considered a rare plant in the 

 United States, occurring only in a very limited area in Pima and 

 Santa Cruz Counties in Arizona. It is probable that it will never 

 become an erosion control plant of significance but the great im- 

 portance of this plant and its near relative, M, e sculent a in the 

 Tropics for the production of cassava and starch, make it worthy of 

 mention. In Arizona it grows as a perennial herb in extremely 

 rocky sites. The growing tubers push their way into all sorts of 



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