FLOWERING PLANTS AND FFRNS OF ARIZONA 415 



2. Branches usually armed with stout, curved spines; pinnae 1 to 3 pairs; 



leaflets 2 to 7 pairs, oblong or obovate, obtuse or retuse, pilose, rarely 

 glabrous; pods not very flat, often somewhat twisted and torulose. 



2. A. GREGGII. 



1. Inflorescence capitate (3). 



3. Flowers distinctly pedicelled; calyx undulate or very shallowly dentate; 



corolla and stamens white or whitish; pods rather promptly dehiscent, 

 flat, thin- walled, not or scarcely torulose; leaflets glabrous or sparsely 

 ciliate; stems woody below or almost completely herbaceous above the 

 crown, unarmed, commonly pilose or hirsute: Section Acaciella (4). 

 4. Leaflets acute and strongly cuspidate at apex, 7 to 9 mm. long, 2.5 mm. 

 wide, strongly pinnate-veined 3. A. lemmoxi. 



4. Leaflets obtuse or acutish, seldom more than 6 mm. long_ _ 4. A. hirta. 

 3. Flowers sessile or nearly so; calyx deeply dentate; corolla and stamens 



bright yellow; pods indehiscent or tardily dehiscent; shrubs or small 

 trees, usually armed with straight or nearly straight, commonly slender 

 spines (5). 



5. Pods turgid, woody, somewhat curved, not conspicuously torulose, 4 to 



7 cm. long, less than 10 times as long as wide; leaflets 10 to 25 pairs: 



Section Yachellia 5. A. farxesiaxa. 



5. Pods compressed, not woody, strongly torulose, more than 10 times as 

 long as wide; leaflets 6 to 12 pairs: Section Acaciopsis (6). 

 6. Plant not, or scarcely, viscid, usually pilose; pinnae seldom fewer and 

 often more than 3 pairs; bracts and calyx teeth ciliate; pods 6 to 



12 cm. long 6. A. coxstricta. 



6. Plant very viscid, glabrous or nearly so; pinnae 1 to 3 pairs; bracts and 

 calyx teeth glandular-denticulate, not ciliate; pods usually not more 

 than 6 cm. long 7. A. verxicosa. 



1. Acacia millefolia S. Wats., Amer. Acad. Arts and Sci. Proc. 21: 427. 



1886. 



Senegalia millefolia Britt. and Rose, North Amer. Fl. 23: 111. 

 1928. 



Cochise and Pima Counties, 3,500 to 4,500 feet, July and August, 

 apparently rare. Southern Arizona and northern Mexico. 



2. Acacia greggii A. Gray, PL Wright, 1: 65. 1852. 



Senegalia greggii Britt. and Rose, North Amer. Fl. 23: 110. 

 1928. 



Coconino County (bottom of the Grand Canyon) and Mohave 

 County to Greenlee, Cochise, Pima, and Yuma Counties, 4,500 feet 

 or lower, often forming thickets along streams and washes, April to 

 October. Texas to southern Nevada, Arizona, southeastern Cali- 

 fornia, and northern Mexico. 



Catclaw acacia, devilsclaw. A common, often abundant, large 

 shrub or small tree, reaching a height of 6 m. (20 feet) and a stem 

 diameter of 20 cm., the sapwood yellow, the heartwood reddish brown. 

 The new foliage is relished by cattle in early spring, otherwise catclaw 

 is valuable chiefly as a reserve food in times of drought or on depleted 

 ranges. The Arizona Indians made meal of the pods, using it as 

 mush and cakes. The flowers are one of the most important sources 

 of honey for bees kept on the desert. The wood is very strong and is 

 used locally for making doubletrees and singletrees, as well as for 

 firewood. This is probably the most heartily disliked plant in the 

 State, the sharp strong prickles tearing the clothes and lacerating the 

 flesh. 



286744°— 42- 



