Palo Verde 



545 



slender spines often 2.5 cm. long. The leaves are about 2.5 cm. long, usually 

 composed of i pair of short pinnae on a hairy 

 stalk 5 to 7 mm. long; pinnae 1.5 to 2.5 cm. 

 long, stalked, bearing 2 to 4 pairs of leaflets, 

 which are obovate or oblong-obovate, 4 to 6 

 nan. long, obtuse or notched at apex, nearly 

 sessile, and somewhat glandular. The flowers 

 appear with the leaves and continue for several 

 months, so that ripe fruit and flowers are fre- 

 quently found on the branches in mid-summer; 

 they are in 3- to 5-flowered racemes, on slender 

 stalks; the calyx- lobes are oblong, reflexed and 

 deciduous; corolla 2 cm. across; petals broad, 

 the standard orbicular to reniform, the others 

 obovate to orbicular; ovary smooth. The fruit 

 is flat, linear-oblong, 4 to 6 cm. long, straight 

 or nearly so, narrowed toward each end, 

 smooth, brownish yellow, splitting into 2 thin 

 valves which are lighter within and expose 2 or 3 longitudinally placed seeds, which 

 are flattened, oval, i cm. long, brownish yellow with darker sides and shining. 



The wood is soft, close-grained, greenish yellow and satiny; its specific gravity 

 is about 0.54. It is used for fuel. 



Fig. 503. — Green Barked Acacia. 



2. PALO VERDE — Cercidium Tomyanum (S. Watson) Sargent 



Parkinsonia Torreyana S. Watson 



Also called Green-barked acacia, and very similar to the tree just described, but 

 perhaps more upright and irregularly branched. It is 

 larger and occurs in the desert regions of Arizona, 

 southern California, Sonora, and Lower CaUfomia, 

 where its brilliant flowers and green branches, even 

 when devoid of foliage, are in strange contrast with the 

 dreary surroundings. It attains a maximum height of 

 9 meters, with a trunk diameter of 5 dm. 



The bark of old trees is 3 mm. thick, at times slightly 

 furrowed, and scaly, but usually, as on the branches, 

 smooth and bright green. The twigs are somewhat zig- 

 zag, smooth, light yellow or pale green and glaucous, 

 armed with spines 8 to 10 mm. long. The leaves ap- 

 pear in March or April, and fall off soon afterward, 

 sometimes a second crop unfolds after an autumnal 

 rain; they are pale hairy on expanding, about 2.5 cm. 

 long, composed of i pair of short pinnse on a slender smooth stalk 5 tc 7 mm. 



Fig. 504. — Palo Verde. 



