492 MISC. PUBLICATION 4 2 3, U. S. DEPT. OF AGRICULTURE 



1. Alhagi camelorum Fisch., Hort. Gorenk. ed. 2, 72. 1812. 



Dinnehotso (Navajo County), along the Little Colorado River in 

 scattered colonies sometimes of considerable extent (Coconino 

 County), near Gillespie Dam (western Maricopa County), along 

 streams and canals, in fields, and on rocky hillsides, May. Introduced 

 into the southwestern United States from Asia. 



Of great value as a browse plant in the desert regions of Asia, but a 

 dangerous introduction, as it is extremely difficult to eradicate from 

 cultivated fields, having deep and extensive rootstocks. In Persia 

 and Afghanistan an exudate, similar to the drug manna that is obtained 

 from Fraxinus ornus L., is collected from the camelthorn. The 

 identification of the Arizona specimens as A. camelorum is perhaps 

 questionable. 



44. NISSOLIA 



Plants with twining or trailing stems, often suffrutescent ; leaves 

 pinnate, the leaflets commonly 5 ; flowers few, axillary, in short racemes 

 or fascicles, the corolla yellow; fruit (loment) few-jointed, sometimes 

 reduced to a single segment, the terminal segment winged, samaralike. 



Key to the species 



1. Stems prostrate or ascending; leaflets not more than 15 mm. long; calyx tube 

 pubescent, longer than the triangular teeth; fruit turgid, commonly 2- or 

 3-seeded and deeply constricted between the seeds, straight, the terminal 

 winglike segment smaller (often much smaller) than the others. 



1. N. WISLIZENI. 



1. Stems twining; leaflets up to 30 mm. long; calyx tube glabrous, equaling or 

 shorter than the subulate teeth; fruit flat, commonly 1- or 2-seeded and 

 scarcely constricted between the seeds, somewhat falcate, the terminal 

 wing much larger than the body of the fruit 2. N. schottii. 



1. Nissolia wislizeni A. Gray, Linn. Soc. London Jour. Bot. 5: 25. 



1861. 

 Cochise County, about 5,000 feet, July and August. Southeastern 

 Arizona and Mexico. 



2. Nissolia schottii (Torr.) A. Gray, Linn. Soc. London Jour. Bot. 5: 26. 



1861. 



Chaetocalyx schottii Torr., U. S. and Mex. Bound. Bot. 56. 1859. 



Pima County, chiefly in the Rincon, Santa Catalina, Tucson, and 

 Baboquivari Mountains, 2,500 to 4,000 feet, July and August. 

 Southern Arizona and northern Mexico. 



45. AESCHYNOMENE. Sensitive-jointvetch 



Plant herbaceous and annual (in Arizona); stems tall, leafy, erect; 

 leaves pinnate with many linear leaflets, these sensitive; flowers in 

 short axillary racemes, the corolla yellow; fruit (loment) narrow, flat, 

 of 3 or more segments, deeply indeuted between the seeds below but 

 not above. 



1. Aeschynomene americana L., Sp. PL 713. 1753. 



Sycamore Canyon near Ruby, Santa Cruz County, about 3,500 feet 

 (Goodding 408, Kearney and Peebles 14462), locally abundant, Septem- 

 ber. Widely distributed in tropical America. 



The Arizona specimens are rather exceptional in their sparse pubes- 



