FLOWERING PLANTS AND FERNS OF ARIZONA 419 



Key to the species 



1. Stems decumbent or spreading; stipules 1 to 2 mm. long, sometimes wanting; 

 leaves 3 to 5 cm. long, the leaflets c^liate, at least when young; peduncle 



not more than 2 cm. long; pods few or solitary 1. D. cooleyi. 



1. Stems erect or ascending; stipules commonly more than 2 mm. long; leaves 4 

 to 10 cm. long, the leaflets glabrous; peduncle 2 to 5 cm. long; pods usually 

 several or numerous (2) . 

 2. Pinnae 1 to 7 pairs; petiolar gland oblong or elliptic, usually borne just 

 below the lowest pair of pinnae and not subtended by stipels. 



2. D. VIRGATUS. 



2. Pinnae 7 to 13 pairs; petiolar gland suborbicular, borne near the base of the 

 petiole, subtended by a pair of subulate stipels 3. D. bicorxutus. 



1. Desmanthus cooleyi (Eaton) TreL, Ark. Geol. Survey Rpt. 1888. 



4: 178. 1891. 



Acacia cooleyi Eaton, Man. ed. 5, 89. 1829. 



Desmanthus jamesii Ton*, and Gray, Fl. North Anier. 1: 402. 



1840. 

 Acuan cooleyi Britt. and Rose. North Amer. Fl. 23: 134. 1928. 



Apache. Navajo, and Coconino Counties, south to Cochise, Santa 

 Cruz, and Pima Counties, 3.500 to 5.500 feet, dry slopes, mesas, and 

 plains. May to September. Nebraska to Arizona and northern 

 Mexico. 



2. Desmanthus virgatus (L.) Willd., Sp. PL 4: 1047. 1806. 



Mimosa rirgata L.. Sp. PI. 519. 1753. 



Acuan virgatum Medik.. Theod. Sp. 62. 1786. 



Guadalupe Canyon. Cochise County, about 4.000 feet (Goodding 

 8330. A9734), Baboquivari Mountains, Pima County (Gilman B6j. 

 Widely distributed in tropical and subtropical America. 



3. Desmanthus bicornutus S. Wats., Amer. Acad. Arts and Sci. 



Proc. 21: 426. 1886. 



Acuan bicomutum Britt. and Rose, North Amer. Fl. 23: 136. 

 1928. 



Near Ruby, Santa Cruz County, about 4.000 feet (Goodding in 

 1938) , August and September. Southeastern Arizona and Chihuahua. 



6. PROSOPIS. 6i Mesquite 



Shrubs or small trees, usually armed with straight spines; leaves 

 with 2 to 4 pinnae, and numerous narrow leaflets: flowers in cylindric 

 spikes, small, greenish yellow, somewhat fragrant; pods indehiscent. 

 compressed but somewhat turgid, or spirally coiled. 



Key to the species 



1. Pods not coiled, compressed, more or less constricted between the seeds, much 

 more than 4 cm. long; leaflets commonly many more than 9 pairs; spines, 

 if any, yellowish, often stout 1. P. juliflora. 



1. Pods tightly spirally coiled, 2 to 4 cm. long; leaflets 5 to 9 pairs; spines white, 

 slender; herbage sparsely to copiously grayish pubescent. 2. P. odorata. 



;: Reference: BuRFART, A. MATERIALES PARA UNA MOXOGRAFIA DEL GEXERO PROsOPIS aEGUMIXOSAKj. 



Darwiniana 4: 57-128. 194U. 



