LEGUMINOSAE 



Blue Paloverde. Greenbarked-acacia 



Cercidium floridum Benth. [Cercidium torreyanum 

 (Wat.) Sarg.] 



HABIT. A thorny shrub or small tree 15-30 feet high; wide, 

 irregular, open crown with stout, tortuous branches. 



LEAVES. Alternate; doubly and evenly pinnate with 2-3 

 pairs of oblong, obtuse, glaucous leaflets K2~/^ inch long; few 

 and totaling less area than green twigs; falling soon, but frequently 

 bearing a second crop during the rainy season. 



FLOWERS. Nearly regular; perfect; in conspicuous 4-5- 

 flowered, axillary racemes; on slender pedicels %-l inch long; 

 calyx 5-lobed, reflexed; corolla of 5, clawed, bright yellow 

 petals, % inch in diameter; stamens 10, free, exserted. 



FRUIT. Oblong, compressed or somewhat turgid legume 

 3-4 inches long and Y^-Yi inch wide; straight or somewhat con- 

 tracted between the 2-8 seeds. Seed: ovoid, compressed. 



TWIGS. Stout; glabrous and glaucous; light yellow or pale 

 olive-green; armed with thin spines K inch long. 



BARK. Thin {Yq inch); smooth and pale olive-green on 

 young trunks, becoming furrowed, scaly, and red-brown. 



WOOD. Unimportant; soft; weak; close-grained; ring-porous; 

 heartwood light brown; sapwood yellow; used as fuel. 



SILVICAL CHARACTERS. Lower Sonoran zone; intoler- 

 ant; abundant seeder; typical of arid, desert sinks, canyons, and 

 depressions; in sandy or gravelly soil. 



GENERAL. Two other species may reach tree size in the 

 Southwest : 



1. Yellow Paloverde, C. microphyllum (Terr.) R. & J., in California 

 and Arizona has leaves with 4-6 pairs of leaflets; a 1-2 seeded 

 legume; and twigs terminating in spines. 



2. Border Paloverde, C. macrum Johnst., in southern Texas has slightly 

 glandular leaflets, \{f^ inch long, and a 2-3 seeded legume. 



The distribution map inchxdcs floridum and microphyllum in Arizona 

 and California and macrum in Texas. 



* * * 



Jerusalem-Thorn 



Parkinsonia aculeata L. 



Jerusalem-thorn is a similar small tree ranging from southern 

 Arizona and Texas to South America. It differs from Paloverde 

 in having a linear, terete legume and leaves with 25-30 pairs 

 of small leaflets and a spinescent rachis. 



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