2. Indigofera suffruticosa Mill. Indigo. 



Erect stems 5-20 dm. tall; leaflets 9 to 15, opposite or nearly so on the 

 rachis, sparsely strigose; racemes shorter than the leaves; calyx less than half 

 as long as the corolla, the teeth lanceolate or deltoid and not or only slightly 

 exceeding the calyx tube; pods (when mature) 15-20 mm. long, acute basally. 



Local in silty often wet alluvial soils in the Tex. Coastal Plains from Hardin 

 Co. to Cameron Co. and inland to Brazos, Gonzales and Wilson cos., July-Nov.; 

 nat. to trop. Am., now widely introd. 



This species and /. tinctoria L. are the sources of the substances which are the 

 chemical precursors of the blue dye indigo, formerly important in commerce. 



11. Amorpha L, 



Unarmed erect shrubs, often rhizomatous, the herbage and calyx often gland- 

 dotted; leaves alternate, deciduous, usually 8 cm. or more long, once-imparipin- 

 nate with 7 or more leaflets; leaflets (4-) 5-30 mm. broad; stipules setaceous, 

 caducous; stipels present; flowers in dense spikelike racemes; calyx obconoid, 

 5-toothed, persistent; corolla very irregular, reduced to 1 petal (the uppermost 

 one, banner), the rest absent, this banner purplish, bluish or whitish; stamens 

 10, exserted; filaments all united briefly at the base, free for most of their length; 

 fruit 4-8 mm. long, gland-dotted, not much if at all compressed, slightly ex- 

 serted from the calyx, 1- or 2-seeded, very tardily dehiscent or seemingly 

 indehiscent. 



A genus of about 20 species in the temperate regions of North America. 



1. Branchlets and leaf rachis with pricklelike glands; calyx lobes triangular- 

 lanceolate, nearly equaling the tube 1. A. californica. 



1. Branchlets and leaf rachis without pricklelike glands; calyx lobes mostly 



short-triangular, much shorter than the tube (2) 



2(1). Branchlets and the conspicuously veiny lower leaf surface tomentose; 



flower spike usually 2-4 dm. long; fruit densely pubescent 



2. A. paniculata. 



2. Branchlets and the inconspicuously veiny lower leaf surface glabrous to some- 



what pubescent; flower spike usually much less than 2 dm. long; 

 fruit usually glabrous (3) 



3(2). Petiolules 3-5 mm. long, usually pubescent and conspicuously glandular; 

 calyx tube pubescent 3. A. texana. 



3. Petiolules about 2 mm. long, not glandular-warty; calyx tube mostly glabrous 



or glabrescent 4. A. fruticosa. 



1. Amorpha californica Nutt. Stinking-willov^^, mock locust. 



Shrub 1-3 m. high, the branches pubescent and beset with scattered prickle- 

 like glands; leaves 1-2 dm. long, ascending; petioles (about 1 cm. long) and 

 leaf rachis pilose and with scattered pricklelike glands; leaflets 1 1 to 25, broadly 

 oval to elliptic, rounded at both ends or retuse and mucronate at apex, 1-3 cm. 

 long, pilose throughout; racemes 5-20 cm. long, the rachis pilose; calyx 5-6 

 mm. long, densely pilose, 10-grooved, the lanceolate lobes nearly equaling the 

 tube; standard reddish-purple, obovate-cuneate, 5 mm. long; pod curved on the 

 back, 8 mm. long, 3 mm. wide, puberulent and conspicuously glandular-dotted. 



Mostly along streams and in river valleys, in N. M. (widespread) and Ariz. 

 (Yavapai, Graham, Cochise and Pima cos.), June; also Calif, and Baja Calif. 



2. Amorpha paniculata T. & G. 



Stout shrub 2-3 m. tall; branchlets sulcate, tomentose; leaves 20-35 cm. long; 

 petioles 4-5 cm. long; leaflets 15 to 19, ovate or oblong, 3-8 cm. long, (15-) 

 20-30 mm. broad, rounded at both ends or rarely emarginate apically, when 



1055 



