376 CONTRIBUTIONS FROM THE NATIONAL, HERBARIUM. 



12. Acacia sororia Standi. Contr. U. S. Nat. Herb. 20: 186. 1919. 

 Queretaro ; type from Higiierillas. 



Leaflets one pair, oval or orbicular, 1 to 2.5 cm. long, coriaceous, puberulent ; 

 fi-uit strongly compressed, bivalvate, 1.5 to 2.5 cm. wide, puberulent. 



13. Acacia conzattii Standi. Contr. U. S. Nat. Herb. 20: 186. 1919. 



Known only from the type locality, Estaci6n Almaloyas, Oaxaca, altitude 

 800 meters. 



Pinnae one pair, the leaflets 2 pairs, 1.5 to 2.5 cm. long; spikes long and 

 slender. 



14. Acacia pringlei Rose, Contr. U. S. Nat. Herb. 3: 316. 1895. 

 Oaxaca and Guerrero ; type from Tomellln Canyon, Oaxaca. 



Tree, 6 to 9 meters high ; leaflets 1.5 to 5 cm. long, bright green, glabrate ; 

 spikes sometimes 12 cm. long ; fruit about 15 cm. long, glabrous. 



15. Acacia calif omica T. S. Brandeg. Proc. Calif. Acad. II. 3: 221. 1892. 

 Southern Baja California ; type from La Palma. 



Tree, 5 to 8 meters high, with very short stout spines; pinnae one pa.r, the 

 leaflets 2 pairs, oval or rounded, 1 to 3 cm. long, thick ; flowers cream-colored, 

 the spikes 5 to 10 cm. long. " Guamuchilillo." 



16. Acacia unijuga Rose, Contr. U. S. Nat. Herb. 8: 32. /. 8. 1903. 

 Known only from the type locality. Las Palmas, San Luis Potosl. 



Large tree, armed with very short spines ; leaflets 2 to 3 cm. long ; spikes very 

 slender and interrupted ; fruit flat, 1.7 to 2.5 cm. wide, puberulent. 



17. Acacia willardiana Rose, Contr. U. S. Nat. Herb. 1: 88. 1890. 



Prosopis heterophyUa Benth. Loud. Journ. Bot. 5: 82. 1846. Not Acacia heter- 

 ophylla Willd. 1805. 



Sonora (type locality) and Baja California. 



Slender unarmed tree, 3 to 5 meters high, the bark exfoliating in thin yellow- 

 ish papery sheets ; leaflets pale green, 2 to 6 mm. long, soon deciduous from the 

 persistent petiole; flowers pale yellow, the spikes 3 to 6 cm. long; fruit flat. 

 0.8 to 1.5 cm. wide, glabrous. " Palo liso," " palo bianco " (Sonora). 



18. Acacia amentacea DC. Prodr. 2: 455. 1825. 

 Acacia rigidula Benth. Lond. Journ. Bot. 1 : 504. 1842. 

 Nuevo-Leon, Tamaulipas, and San Luis Potosl. Southwestern Texas. 

 Shrub or small tree, 3 to 4.5 meters high ; spines straight, sometimes 5 cm. 



long ; pinnae 1 pair, the leaflets few, oblong, about 1 cm. long, lustrous ; spikes 

 short, the flowers yellow, sweet-scented ; fruit 3 to 4 mm. wide, compressed, 

 brown, puberulent. " Gavia " (Tamaulipas); " chaparro prieto " (Nuevo Le6n, 

 Tamaulipas). 



19. Acacia bilimekii Macbride, Contr. Gray. Herb. n. ser. 59: 6. 1919. 

 Acacia sericocarpa Rose, Contr. U. S. Nat. Herb. 8: 300. 1905. Not A. seri- 



cocarpa Fitzg. 1904. 

 Acacia ambigua Rose, Contr. U. S. Nat. Herb. 8: 31. i. 7. 1903. Not A. am- 



Ugtca Hoffmg. 1826. 

 Morelos and Puebla ; type from Matamoros, Puebla. 



Low -shrub, densely pubescent; spines 1 to 2 cm. long, whitish; leaflets ob- 

 long, about 1 cm. long ; fruit 5 mm. wide. 



20. Acacia sonorensis Rose, Contr. U. S. Nat. Herb. 8: 31. 1903. 

 Known only from the type locality, Guaymas, Sonora. 



Shrub ; pinnae one pair, the leaflets 2 or 3 pairs, oblong, 6 to 12 mm. long. 



21. Acacia greggii A. Gray, PI. Wright. 1: 65. 1852. 



Chihuahua and Coahuila ; type from valley west of Patos. Western Texas 

 to southern Arizona. 



