LEGUMINOS^E 



571 



especially on the entire wavy margins, hoary-pubescent, f'-l' long, \'-% wide, with 

 broad midribs and three pairs of lateral ribs, on vigorous young shoots or seedling 

 plants remotely and coarsely serrate, remaining only for a few weeks on the 

 branches; stipules minute, ovate, acute, pubescent. Flowers ^' long, appearing in 

 June on short pedicels from the axils of minute bracts, in racemes I'-l^' long, their 

 rachises slender, spinescent, hoary-pubescent; calyx-tube 10-ribbed, with usually 5 

 glands between the dorsal ribs, the lobes short, ovate, rounded or more or less ciliate 

 on the margins, reflexed at maturity; petals dark violet blue; standard cordate, 

 reflexed, furnished at the base of the blade with two conspicuous glands, wings and 



keel attached to the staminal tube by their bases only and nearly equal in size, 

 rounded at the apex, more or less irregularly lobed at the base; ovary pubescent, 

 glandular-punctate. Fruit ovate, pubescent, glandular, twice as long as the calyx, 

 tipped with the remnants of the recurved style ; seed \' long, pale brown irregu- 

 larly marked with dark spots. 



A tree, 18-20 high, with a short stout contorted trunk sometimes 20' in diam- 

 eter and divided near the ground into several upright branches, and branchlets 

 reduced to slender sharp spines coated with fine pubescence, bearing minute nearly 

 triangular scarious caducous bracts, marked by occasional glandular fistules, and 

 developed from stouter branches hoary-pubescent when young, becoming glabrous 

 in their third year and covered with pale brown bark roughened with lenticels and 

 as it exfoliates showing the pale green inner bark; more often a low rigid intricately 

 branched shrub. Bark of the trunk dark gray-brown, nearly \' thick, deeply fur- 

 rowed, and roughened on the surface by small persistent scales. Wood light, soft, 

 rather close-grained, walnut-brown in color, with nearly white sap wood of 12-15 

 layers of annual growth. 



Distribution. Valley of the lower Gila River, Arizona, to the Colorado Desert 

 of California, and southward into Sonora and Lower California. 



15. ROBINIA, L. Locust. 



Trees or shrubs, with slender terete or slightly many-angled zigzag branchlets, 

 without terminal buds, minute naked subpetiolar depressed-globose axillary buds 

 3 or 4 together, superposed, protected collectively in a depression by a scale-like 



