48 FIELD MUSEUM or NATURAL HISTORY BOTANY, VOL. IV. 



Broadhead (Hb. Mo. 85553). ARKANSAS: Fulton, B. F. Bush 2408 

 (Hb. Mo. 85375). SOUTH DAKOTA: Deadwood, waste ground, alt. 1430 

 m., John Murdoch, Jr., 4334 (Hb. Gray). KANSAS: Kiowa County, low 

 ground, A. S. Hitchcock 726 (Hb. Gray; Hb. Mo. 85525). OKLAHOMA: 

 Hugo, moist limestone soil, E. J. Palmer 9015 (Hb. Mo. 794481). 

 TEXAS: Dallas, prairie, B. F. Bush 1185 (Hb. Gray; Hb. Mo. 85380; 

 type specimens of X. bubalocarpon Bush); Pease River, near Vernon, 

 salt bottoms, Sept. 18, 1903, H. Eggert (Hb. Mo. 85558 and 85559); 

 Dallas, Oct. 10, year not stated, /. Reverchon (Hb. Mo. 85557); Coombs 

 Branch, Aug. 24, 1901, idem (Hb. Mo. 85556 and 85562); Coombs 

 Branch, Oct. 9, year not stated, idem, (Hb. Mo. 85479) ; Dallas, prairie, 

 Aug. 30, 1901, idem (Hb. Gray; Hb. Mo. 85378); Dallas, prairie, idem 

 2580 A (Hb. Mo. 85379); Luck's Mill, Aug. 25, year not stated, idem 

 (Hb. Mo. 85560 and 85561); Oak Cliff, wastes, Aug. 30, 1901, idem 

 (Hb. Mo. 85376 and 85377). l 



While appearing in rare cases to intergrade or perhaps hybridize 

 with X. oviforme Wallr., X. speciosum seems, nevertheless, on the whole 

 to be worthy of retention as a distinct species. It is apparently best 

 distinguished from that species by the closer, more slender and less 

 arcuate prickles, which do not suggest horns, and by a tendency of the 

 entire involucre, when mature, toward a yellowish or yellowish-brown 

 color rather than toward the dark-reddish color shown in X. oviforme. 



The several sheets of type material (Kearney 785) that we have 

 examined are of a slightly immature stage and the burs are not fully 

 ripened. But Kearney (loc. tit.} described the burs as "2.5-4 cm. long, 

 2.5-3 cm ' wide (including the prickles) " and, as some of the slightly 

 immature burs are observed by us on the type material to have become 

 3.5 cm. long and 2.5 cm. wide (including the prickles), it is certain that 

 Kearney's measurements correctly represent the mature fruits. 



In describing his X. bubalocarpon, Bush (loc. tit.} stated: "This 

 very distinct species is more nearly related to X. speciosum Kearney, 

 but is easily distinguished from that species by the much larger burs 

 which are of an entirely different shape." However, on reading his 

 description, we find given the measurements " 2.5-4 cm. long, including 

 the prickles." It is seen that these measurements are practically 

 identical with those given by Kearney for X. speciosum. And, indeed, 

 when we compare the excellent type material of X. bubalocarpon (Bush 

 1185) with that of X. speciosum, we can detect no specific difference. 



1 We have seen no typical material of X. speciosum from Mexico. Certain some- 

 what anomalous forms from there appear, however, to be best regarded as belonging 

 to this species (e.g., J. N. Rose 2433, near San Juan Capistrano, Zacatecas, Hb. U. S. 

 301344; Rose, Painter and Rose 0032, near Tehuacan, Puebla, Kb* U. S. 453446). 



