374 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



The spines are very different from tliose of any other species. Palmer re- 

 ports that a decoction of the plant is used in Sonora as a remedy for affec- 

 tions of the bladder, 



2. Acacia macracantha Humb. & Bonpl. ; Willd. Sp. PI. 4: 1080, 1806. 

 Mimosa lutea Mill. Gard. Diet. ed. 8. Mimosa no. 17, 1768. 



Acacia lutea Hitchc. Rep. Mo. Bot. Gard. 4: 83. 1893. Not A. lutea Leavenw, 

 1824. 



Sinaloa to Puebla and Veracruz. Central America, West Indies, and South 

 America. 



Shrub or small tree ; spines 2.5 to 5 cm. long, compressed, brown or gray ; 

 leaflets numerous, linear, about 2 mm. long; flowers yellow, the heads about 

 8 mm. in diameter ; fruit 10 to 12 cm. long, somewhat compressed, dark brown, 

 tai'dily if at all dehiscent. 



3. Acacia standleyi Safford, Journ. Washington Acad. Sci. 4: 367. 1914. 

 Known only from the type locality, Acaponeta, Tepic. 



Shrub ; spines 2.5 to 3.5 cm. long, castaneous or grayish, slightly compressed ; 

 leaflets about 3 mm. long ; flowers yellow, the very dense spilies 2 cm. long. 



4. Acacia gladiata Safford, Journ. Washington Acad. Sci. 5 : 359. f. 2. 1915. 

 Sinaloa and Tepic; type from Rosario, Sinaloa. 



Spines 3.5 to 5 cm. long, almost flat, brown or gray ; leaflets 3 to 4 mm. long. 

 Probably only a form of A. standleyi. 



5. Acacia sphaerocephala Schlecht. «&; Cham. Linnaea 5: 594. 1830. 

 Acacia veracruzensis Schenck, Repert. Sp. Nov. Fedde 12:362. 1913. 

 Acacia dolichocephala Safford, Journ. Washington Acad. Sci. 5: 355. 1915. 

 Tamaulipa.s, San Luis PotosI, Veracruz, and Yucatan. 



Shrub or small tree, sometimes 6 meters high ; spines mostly 4 to 11 cm. long, 

 terete or nearly so, whitish, pale brown, or yellowish ; leaflets oblong-linear, 5 

 to 8 mm. long; flowers yellow; fruit about 5 cm. long, red or reddish brown, 

 with a very long sharp beak. " Comezuelo " (Tamaulipas) ; "zubin," "zubin- 

 ch4" (Yucatan, Maya). 



The seeds are imbedded in abundant pulp. In this, as in the following species 

 (nos. 6 to 10), the bull-horn acacias, the large spines are usually inhabited by 

 ferocious ants, which enter the spines by a puncture near the apex. These ants 

 subsist upon nectar of the large pale ghinds which are borne as appendages upon 

 the tips of the leaflets. 



6. Acacia comigera (L.) Willd. Sp. PI. 4: 1080. 1806, 

 Mimosa comigera L. Sp. PI. 520. 1753. 



Acacia spadicigera Schlecht. & Cham. Linnaea 5:595. 1830. 



Acacia hernandezii Safford, Journ. Washington Acad. Sci. 4:358. 1914. 



Acacia furcella Safford, Journ, Washington Acad. Sci. 4: 359. 1914. 



San Luis Potos-i and Veracruz to Chiapas, and probably elsewhere ; described 

 from a cultivated plant of Mexican origin. Central America. 



Shrub or small tree ; spines 2.5 to 10 cm. long, terete or slightly compressed, 

 varying in color from brownish yellow to almost black, often recurved or 

 twisted; leaflets about 8 mm. long, glabrous, the nectar glands 1 to 2 mm. long; 

 flowers yellow, the very dense thick spikes 2.5 to 4 cm. long ; fruit 2.5 to 6 cm. 

 long, red or brown at maturity. " Espino bianco " (Chiapas) ; " zubin," " zubin- 

 cM" (YucatS.n, Maya, Seler) ; " cornezuelo " (Tabasco, Rovirosa, Nicaragua) ; 

 "cuernos del toro " (Oaxaca) ; " Srbol del cuerno " (Veracruz); " cuernitos " 

 (Veracruz, Oaxaca); " huitzmamaxalli " of Hernandez; " iscanal bianco" (El 



