OLNEYA BEANS 



A Native Food Product of the Arizona Desert, Worthy of Domestication 



O. F. Cook 

 Bionomist in Charge of Crop Acclimatization, U. S. Department of Agriculture 



SO many different trees are called 

 ironwood in other parts of the 

 United States that further use of 

 this name for Olneya tesota should 

 be avoided. As the tree is confined to 

 the southwestern deserts, names like 

 "desert ironwood," "southwestern iron- 

 wood," or "Sonora ironwood," the last 

 proposed in Britton's "Trees of North 

 America," might serve, but such com- 

 pounds are too awkward and tedious in 

 repetition to be used consistently. 

 The Mexican name, palo fierro or arbol 

 de hierro, meaning iron tree, may come 

 into use, since palo verde, meaning 

 green tree, has been adopted generally in 

 the southwest for another leguminous 

 tree (Cercidium), which is a regular 

 companion of Olneya in the desert. 

 But palo fierro and arbol de hierro are 

 not more distinctive names in Spanish 

 than ironwood in English, and are 

 applied to trees of many kinds in 

 Mexico and other parts of tropical 

 America. Use of the generic name 

 Olneya, or the name tesota, recorded 

 by the Mexican boundary explorers and 

 recognized in Gray's botanical designa- 

 tion of the species, would avoid the 

 difficulties. 



The only economic feature of Olneya 

 noted in botanical works of reference is 

 that the wood is very heavy, hard, and 

 difficult to work, though sometimes used 

 for special purposes and generally valued 

 as fuel. Possibilities as an ornamental 

 are suggested by Britton's reference to 

 Olneya as "a most beautiful tree." 

 The grayish foliage and gnarled trunks 

 give a slight similarity to the olive, 

 set off in May by an abundance of 

 pinkish-purple blossoms, in form like 

 those of the locust tree, to which Olneya 

 is related. It is the largest as well as the 

 most attractive tree that grows as a 

 true native of the driest southwestern 



deserts, away from the stream beds and 

 with full exposure to heat and drought. 



A forage value is recognized in ' ' New 

 Trails in Mexico," by Lumholtz, who 

 tells how the mules, donkeys and horses 

 left good grass to feed on the leaves of 

 palo fierro. "They stretched their 

 necks like giraffes in eager competition 

 and, paying no heed to its numerous 

 thorns, they pulled away mouthfuls of 

 leaves." This has to be corrected to 

 the extent that Olneya has no true 

 thorns like those of the mesquite, but 

 as in the screw-bean there are slender 

 spine-like stipules 4 or 5 mm. long on 

 the upright shoots, though the smaller 

 twigs are unarmed. Referring to a 

 district in Sonora, between Santa Ana 

 and Trincheras, Lumholtz also says: 

 For three or four hours we were cross- 

 ing a large, low mesa with a predominant 

 vegetation of palo fierro trees, the 

 leaves of which furnish here the sole 

 subsistence for herds of cattle. They 

 grow fat on this, drinking water only 

 every third day." The flowers also 

 are said to be eaten as they fall to the 

 ground, and to fatten the stock. 



Thus we have Olneya as a handsome 

 flowering tree, with a "dark, heavy, hard 

 wood like ebony, and with foliage and 

 flowers that are eaten with avidity by 

 animals and are nutritious, like alfalfa. 

 To this reckoning must be added the 

 fact that the Olneya trees bear thick 

 crops of pods not unlike those of garden 

 beans, and that each pod may have 

 several seeds, unlike the small bony 

 seeds of the mesquite, but of the size, 

 appearance and texture of small peanuts 

 and having the same agreeable flavor 

 when roasted, so that they can be used 

 as food. Young pods probably could 

 be cooked and eaten like green beans, 

 since the texture is fleshy and the 

 taste not bitter, even in the raw state, 



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