FLOWERING PLANTS AND FERN.- OF ARIZONA 413 



1. Filaments separate to the base or very nearly so, less than 10 mm. long '3 . 

 3. Stamens many more than 10; plants suffrutescent to large shrubs or small 

 trees; flowers in heads or spikes 3. Acacia. 



3. Stamens not more than 10 (4). 



4. Anthers gland-tipped; pods indehiscent. flat or spirally coiled: plants 

 large shrubs or small trees; flowers in spikes 6. Prosopis. 



4. Anthers not gland-tipped " . 



5. Valves of the pod finally separating from the persistent margins, often 



in sections; plants shrubby; stems (and often the pods) prickly; 



flowers in round heads or spikelike racemes 4. Mimosa. 



5. Valves of the pod not separating from the margins: plants suffrutescent; 



stems and pods unarmed; flowers in round heads. _5. Desmanthus. 



1. CALLIAXDRA. False-mesquite 



Plants perennial, herbs or low shrubs, not prickly: flowers in heads, 

 pink or white; stamens many, long and conspicuous; pods with thick 

 riblike margins, the valves recurved after dehiscence. 



These plants are also known as mesquitilla and fairyduster. All 

 of the Arizona species of Calliandra are valuable as soil binders and are 

 palatable to livestock, but O. eriopfiyUa, because of its relatively large 

 size, resistance to browsing, and abundance, far exceeds the other 

 species in economic value, and is highly palatable to deer. 



Key to the species 



1. Stems herbaceous above ground, rarely more than 20 cm. long (2). 



2. Plant glabrous or sparsely pilose; pinnae 1 to 4 pairs: leaflets not more 

 1 usually fewer) than 12 pairs, 7 to 14 mm. long, 3 to 6 mm. wide, obliquely 

 oval or oblong, conspicuously reticulate-veined 1. C. reticulata. 



2. Plant pilose, usually copiously so: pinnae 4 to 9 pairs; leaflets 10 to 18 pairs, 



rarely more than 5 mm. long, 1 to 2 mm. wide, linear or narrowly oblong, 



seldom conspicuously reticulate 2. C. humilis. 



1. Stems woody above ground, commonly more than 20 cm. long (3). 



3. Branches slender, not rigid, erect or ascending at a narrow angle, moderately 



woody; leaflets few (not more than 7 pairs), not imbricate, spreading 

 thin, bright green, glabrous or pubescent, 5 to 12 mm. long, 2 to 5 mm. 

 wide; flowers glabrous; stamens not more than 15 mm. long; pods 



glabrous or inconspicuously puberulent 3. C. schotth. 



3. Branches stout, rigid, often divaricate, very woody; leaflets numerous 

 (usually more than 7 pairs), imbricate, ascending, rather thick, grayish- 

 pubescent, not more than 7 mm. long, 1 to 2 mm. wide: flowers pubes- 

 cent; stamens about 20 mm. long; pods densely and conspicuously 

 pubescent 4. C. eriophylla 



1. Calliandra reticulata A. Gray, PL Wright, 2:53. 1S53. 



Acacia humilis Schlecht., Linnaea 12: 567. 1838. Xot 



Calliandra humilis Benth. 

 Anneslia humilis Britt. and Rose, North Amer. Fl. 23: 57. 



1928. 



Southern Coconino County to Cochise, Santa Cruz, and Pima 

 Counties, 5,500 to 8.000 feet, commonly in dry pine forests. May to 

 September. New Mexico, Arizona, and Mexico. 



2. Calliandra humilis Benth., London Jour. Bot. 5: 103. 1846. 



Calliandra kerbacea Enselm., Amer. Acad. Arts and Sci. Mem. 



ser. 2, 4: 39. 1849. 

 Anneslia kerbacea Britt. and Rose, North Amer. Fl. 23: 57. 



1928. 



Navajo and Coconino Counties to Cochise, Santa Cruz, and Pima 

 Counties. 4.000 to 9.000 feet, dry soil among oaks or pines, June to 

 August. Western Texas to Arizona and northern Mexico. 



