426 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



perhaps an escape from cultivation, 2,000 to 3,000 feet, May (probably 

 other months). Florida, southern Texas, and southern Arizona, to 

 South America. 



A very attractive, rapid-growing plant, much used for ornamental 

 planting in warmer parts of the United States. Sometimes known as 

 horsebean. 



11. CERCIDIUM.63 Paloverde 



Large shrubs or small trees, attaining a height of about 8 m. (25 

 feet); young bark smooth, green; rachis of the pinnae short, terete; 

 flowers showy, yellow, in corymbose fascicles; pods more or less 

 torulose. 



The Arizona paloverdes of the genus Cercidium are very common and 

 characteristic plants of the lower and drier parts of the State and are 

 a glorious sight when in full flower. They are leafless in the dry 

 season but always conspicuous because of the green bark. The wood 

 is soft and brittle and burns very quickly, giving off an unpleasant 

 odor and leaving few coals. The pods are fairly palatable but are not 

 much eaten by livestock, except during prolonged droughts. It is 

 stated that the Indians ate the seeds sometimes after grinding them 

 into meal. The flowers are reported to yield good honey. 



Key to the species 



1. Young bark yellowish green; leaves appearing simply pinnate, the common 

 rachis nearly obsolete; leaflets of each pinna commonly 4 to 8 pairs, very 

 small, not more than 3 mm. long; flowers pale yellow, the odd petal often 

 whitish; pod turgid, ending in a flat triangular or sword-shaped beak. 



1. C. MICROPHYLLUM. 



1. Young bark bluish green; leaves evidently bipinnate, the common rachis short 

 but apparent; leaflets of each pinna I to 3 pairs, 4 to 8 mm. long; flowers 

 bright yellow, all of the petals alike in color; pod flat, with a short triangular 

 beak or almost beakless 2. C. floridum. 



1. Cercidium microphyllum (Torr.) Rose and Johnston in Johnston, 



Contrib. Gray Herbarium, ser. 2, 70: 66. 1924. 



Parkinsonia microphylla Torr., U. S. Rpt. Expl. Miss. Pacif . 4: 



82. 1857. 

 Cercidiopsis microphylla Britt. and Rose, North Amer. Fl. 23: 



306. 1930. 



Northern Mohave County to Cochise, Pima, and Yuma Counties, 

 4,000 feet or lower, dry rocky hillsides and mesas, April to May. 

 Southern and western Arizona, southeastern California, Sonora, and 

 Baja California. 



Yellow paloverde. Ends of the leafy branchlets spinescent. 



2. Cercidium floridum Benth. in A. Gray, PI. Wright. 1: 58. 1852. 



Cercidium torreyanum (S. Wats.) Sarg., Gard. and Forest 2: 

 388. 1889. 



Gila, Pinal, and Pima Counties to Mohave and Yuma Counties, 

 3,500 feet or lower, common along washes and on flood plains, less 

 frequently on dry lower slopes, April to May (occasionally August to 

 October). Range outside Arizona same as that of C. microphyllum. 



Blue paloverde. Leafy branchlets not or not strongly spine-tipped, 



« 3 Reference: See under Parkinsonia, p. 425. 



