safford: new bull-horn acacias 355 



BOTANY. — New or imperfectly known species of hull-horn acacias. 

 William Edwin Safford, Bureau of Plant Industry. 



In 1914 the writer published a preliminary paper on the 

 myrmecophilous acacias of tropical America commonly called 

 bull-horns. 1 The present paper is intended as a supplement to 

 it. Additional material has been received from various sources, 

 including specimens from the herbarium of the Missouri Botan- 

 ical Garden collected in Mexico by Dr. Josiah Gregg in 1849, 

 and others from the Isthmus of Panama, collected recently by 

 Mr. Henry Pittier. 



An undescr!bed species very clo ely related to Acacia Standleyi 

 and to A. hirtipes must be assigned to the section Clavigerae. 

 The fact that the large spines of this new species are quite glabrous 

 makes it advisable that the group name Hebacanthae, which 

 includes these species, be changed; and the name Mesopodiales 

 is therefore proposed herewith as a substitute for it. As modi- 

 fied the group may be redescribed as follows: 



Group V. Mesopodiales {Hebacanthae Safford, op. cit., p. 366). 

 Involucel borne at or above the middle of the peduncle of the flower 

 spike. Interfloral bracteoles not peltate, but composed of a fan-shaped 

 or ovate limb with a hairy margin, borne upon a blender pedicel and 

 forming an imbricated pubescent covering over the flowers before 

 anthesis. 



Of the three additional species discussed one belongs to the 

 group Ceratophysae and two to the Globuliferae. 



Acacia dolichocephala Safford, sp. nov. Group Geratophysae, sec- 

 tion Dolichocephalae. A shrub or small tree resembling A caaasp/iaer- 

 ocephala Schlecht. & Cham., but readily distinguished by its elon- 

 gate flower-heads and fusiform receptacle, as well as by the occasional 

 presence of nectar glands on the leaf-rachis at the base of the terminal 

 and subterminal pairs of pinnae. Young growth puberulent, at length 

 glabrate. Stipular spines ivory white, tipped with brown, broadly 

 divergent and slightly curved outward, terete, tapering gradually to 

 a point, the bases flattened and more or less cuneate, the spines 4 to 

 5 cm. long, 10 to 12 mm. broad along the line of union of the connate 

 bases. Leaves of vegetative branches composed usually of 10 pairs 

 of pinnae; rachis puberulent, 10 to 14 cm. long, with an elongated 



1 Safford, W. E., "Acacia cornigera and its allies." Journ. Wash. Acad. Sci. 

 4: 356-386. 1914. 



