FLOWERING PLANTS AND FERNS OF ARIZONA 417 



mesas, May to August (occasionally November). Texas to Arizona 

 and Mexico. 



Abundant over large areas in southeastern Arizona. A pretty 

 shrub, especially when covered with the small orange-yellow balls of 

 very fragrant flowers. The foliage is not palatable to livestock, 

 although the pods are eaten. The plants are mostly well armed with 

 long stender straight white spines, but var. paucispina Woot. and 

 Standi., with few or no spines, is occasionally met with. 



7. Acacia vernicosa Standi., Contrib. U. S. Xatl. Herbarium 20: 187. 

 1919. 



Acaciopsis vernicosa Britt. and Rose, North Amer. Fl. 23: 96. 



1928. 



San Bernardino Ranch, vicinity of Fort Huachuca, and Benson, 

 (Cochise County), 3,500 to 5,000 feet, June to September. Western 

 Texas to southeastern Arizona and Mexico. 



A species generally similar to A. constricta but readily distinguished 

 by the characters given in the key, some of which were brought to the 

 attention of the writers by Ira L. Wiggins (personal communication). 



4. MIMOSA 



Plants shrubby, usually armed; leaves with numerous small leaflets; 

 flowers small, sessile, whitish or pink, in many-flowered heads or spikes; 

 stamens not more than 10; pods with or without prickles, in some 

 species breaking up into 1 -seeded sections. 



These plants are mostly very attractive in flower, and the flowers 

 are commonly fragrant. 



Key to the species 



1. Inflorescence elongate, spicate or racemose; flowers purplish pink; valves of the 

 pods jointed, the segments separating at maturity (2). 

 2. Young stems, leaves, and flowers glabrous or inconspicuously pubescent; 

 spines few or none; pinnae 1 to 4 pairs; leaflets 2 to 5 pairs, elliptic to 

 obovate, rounded and often mucronulate at apex, 5 to 10 mm. long, at 

 least half as wide; flowers short-pediceled; pods very flat, thin- walled, 

 glabrous, unarmed, not, or scarcely, torulose 1. M. laxiflora. 



2. Young stems, leaves, and flowers sericeous or villous; spines numerous; 



pinnae 5 or more pairs; leaflets 7 or more pairs, linear-lanceolate or nar- 

 rowly oblong (the terminal one sometimes obovate), acute or acutish at 

 apex, 3 to 6 mm. long, less than half as wide; flowers sessile; pods not 

 very flat, thickish-walled, tomentose, strongly torulose. 



2. M. DYSOCARPA. 

 1. Inflorescence capitate; flowers pale pink or whitish; valves of the pods not 

 jointed, usually prickly-margined (3). 



3. Spines of the stem stout, conspicuously flattened and broadened to far above 



the base, strongly recurved toward the apex; leaves, including the 

 petiole, 1.5 to 4 cm. long, the pinnae crowded, the internodes of the 

 rachis seldom more than 5 mm. long, the leaflets 2 to 3.5 mm. long, not 

 apparently pinnate-veined; calyx and corolla pubescent; pods 3 to 4 mm. 

 wide, acute or acuminate at apex, more or less curved. 



3. M. BIUXCIFERA. 



3. Spines of the stem relatively slender, conspicuously broadened only near the 

 base, often straight or nearly so; leaves, including the petiole, 5 to 10 cm. 

 long, the pinnae not crowded, the internodes of the rachis commonly at 

 least 6 mm. long, the leaflets 3 to 6 mm. long, distinctly pinnate-veined; 

 pods 5 mm. wide or wider, rounded and often apiculate at apex, straight 

 or nearly so _ 4. M. grahami. 



