Sonora Ironwood 



557 



spicuous veins beneath; the principal veins and the petioles are hairy; the stipules, 

 which are thin and flexible at first, develop into brown-red spines, sometimes 2.5 

 cm. long. The flowers open in May or June in dense, racemes and sometimes 

 again in August; the stout peduncle and slender pedicels and the calyx are cov- 

 ered with glandular hairs. The flowers are pale rose colored, sometimes nearly 

 white; the standard and wing petals are very broad. The pod is narrow, 7.5 to 

 10 cm. long, reddish brown, glandular hairy, tapering at each end, bearing the 

 recurved, persistent style at the apex; the seeds are about 3 mm. long, dark brown 

 and blotched. 



The wood is very hard, strong, close-grained and yellow with brownish mark- 

 ings; its specific gravity is about 0.80. The tree is hardy as far north as the 

 New England States. 



IV. SONORA IRONWOOD 



GENUS OLNEYA A. GRAY 

 Species Olneya Tesota A. Gray 



MOST beautiful tree of wide distribution in the desert regions of 

 the southwestern United States and adjacent Mexico, reaching a 

 height of 9 meters, with a trunk diameter of 4.5 dm. It is called 

 Palo de Hierro and Arbol de Hierro by the Mexicans. 

 The trunk is short and stout, usually forking into several nearly upright 



branches. The bark is thin 



and scaly, peeling off in 



long reddish brown strips. 



The twigs are whitish hairy, 



soon becoming green, 



marked with red and finally 



turning light brown. The 



spines, which are often in 



pairs below the leaves, are 



straight or nearly so, very 



stiff and sharp, 3 to 10 mm. 



long and persist for several 



years. The pinnate leaves 



are somewhat persistent, 2 



to 6 cm. long, consisting of 



10 to 15 leaflets and a slen- 

 der grooved petiole 6 to 10 



mm. long, often fascicled and without stipules; the leaflets are oblong-obovate, 8 



to 20 mm. long, blunt or minutely tipped, wedge-shaped at the base, entire on 



the margin and short-stalked; they are whitish-hair}^, the lower surface conspicu- 



FiG. 515. Sonora Ironwood. 



