APRIL, 1919. XANTHIUM MILLSPAUGH AND SHERFF. 17 



from X. strumarium L.; in the same herbarium is a specimen (Kotschyi 

 iter Nubicum 319, ad ripas Nili albi prope Chartum in provincia Sennar, 

 Mar. 4, 1840) which has slightly longer and more numerous prickles, 

 these more hirsute below than in most other specimens. This is the 

 form cited by Wallroth for his X. antiquorum. 1 It is matched very well 

 by a fine specimen in the Herbarium of Field Museum (Fred S. Meyers 

 215, waste places, Jaffa, Aug. 2, 1902, Hb. Field 162920) coming from 

 Palestine. The distinctions emphasized appear to us, however, too slight 

 and inconstant to warrant maintaining X. antiquorum apart from X. 

 strumarium. Likewise, after examining a number of specimens from 

 India (mainly in Hb. Gray) we are convinced that X. discolor Wallr., 

 X. Roocburghii Wallr. and X. brevirostre Wallr. are merely forms of 

 X. strumarium L. (as indeed they were regarded by Hooker, Fl. Brit. 

 Ind., 3 : 303. i88i). 2 



3. XANTHIUM CHINENSE Mill. Gard. Diet. Edit. VIII, No. 4. 1768. 

 Xanthium chinense Mill. Abridg. Gard. Diet. Edit. VI, No. 4. 



1771. 



Xanthium occidentale Bertol. Lucubr. Herb. 38. 1822. 

 Xanthium macrocarpum var. glabratum DC. Prodr. 5 : 523. 1836. 



ex. descr. 



Xanthium pungens Wallr. Beitr. Bot. i n : 231. 1844. 

 Xanthium longirostre Wallr. loc. cit. 237; Britton Fl. Bermuda 384, 



f. 417. 1918. 

 Xanthium glabratum Britt. Man. 912. 1901.* 



1 Xanthium priscorum Wallr. (loc. cit. 227). Wallroth used the name X. priscorum 

 in his clavis, accompanying it with a short diagnosis; but in the main body of his work 

 and also in the introduction (pp. 221 and 229) he had changed the name to X. anti- 

 quorum. His retention of the name X. priscorum was clearly through an oversight. 

 We may note a similar error in regard to his X. eriocarpon (which is referable to 

 X. ambrosioides Hook. & Arn., for which species Wallroth merely made a new, and 

 in his opinion, more accurate name; we have seen various excellent specimens in 

 Hb. Gray and Hb. N. Y.). Wallroth at first (loc. cit. 229) advanced this species in 

 his clavis under the name X. leucocarpon, with a short diagnosis; but in the main 

 body of his work (p. 242) he had changed the name to X. eriocarpon. 



1 Xanthium inaequilaterum DC., a species with smaller fruits (5-6 mm. long 

 exclusive of the beaks), originally described from material collected near Buitenzorg, 

 Java, is similar to X. strumarium, but its smaller fruits are very distinctive. Several 

 good (topotypic) fruiting specimens exist in Hb. Gray (Zollinger, Batavia, Java, in 

 1849; Teysmann, ex horto bogoriensi, Buitenzorg, Java, in 1869). These are re- 

 markably uniform and appear to indicate that the species X. inaequilaterum DC. 

 is entirely separate from X. strumarium L. 



A number of other species of Xanthium have been described from the Eastern 

 Hemisphere that undoubtedly are mere forms of X. strumarium; however, as 

 opportunity has been lacking to examine authentic material, their names have been 

 omitted from our list of synonyms. 



l Xanthium canadense of Rowlee, not Miller, Bull. Torr. Bot. Club 20 : 10, ff. 

 g-m. 1893. 



f Xanthium carolinense Dill, ex MacMillan, Geol. Nat. Hist. Surv. Minn. Bot. 

 i : 535- 1892. We have not seen the original work of Dillenius, cited by 

 MacMillan, for this reference. 



Xanthium strumarium of Millsp. & Chase, Field Mus. Bot. 3 : 87, f. 1904. 



Xanthium strumarium of Britton & Brown, 111. Fl. 3 : 298, f. 3599. 1898. See 

 also footnote, p. 40. 



