APRIL, 1919. XANTHIUM MILLSPAUGH AND SHERPF. 39 



OTA: Leeds, fields, Aug. i6-Sept. 6, 1899, Dr. J. Lunell (Hb. Gray); 

 Leeds, along running water, Aug. 28, 1902, idem 82 (Hb. Gray). 



This species was badly confused by Wallroth (Beitr. Bot. i n : 239. 

 1844) with the true X. orientale L. Indeed, many other botanists have 

 fallen into similar errors, so that in literature we find X. echinatum 

 erroneously equated with a number of entirely distinct species. Thus, 

 for example, Thellung (Verhandl. Bot. Verein Brandenb. 50": 142-144. 

 1908) actually gives as synonyms, X. italicum Mor., X. pennsylvanicum 

 Wallr., X. riparium Lasch, X. campestre Greene 1 and X. chinense Mill. 



Murray's original description not only was very complete but was 

 accompanied by a good plate. 2 This plate shows the fruiting involucres 

 to have an ovoid body, with short, rather remote prickles and very wide 

 achenes (ff. i, 7 and 8). Thellung (loc. tit.) attempts to differentiate 

 between Murray's description and plate, retaining the former and 



excluding the latter. But Murray's description (" 



Capsula ovalis, olivae magnitudinis, hirsuta, antice hamosa, hamis 

 inflexis hispidis, vestita aculeis uncinatis, divergentibus, consertis, sur- 

 sum et apice nudis, basi deorsum echinatis per setas rigidas albidas, 

 rectiores; bilocularis ") harmonizes perfectly, in our opin- 

 ion, with the plate. Moreover, Murray himself stated that his plant, 

 raised in 1783, came from fruits sent him by Von Wangenheim, from 

 New York. And it is precisely in the Atlantic coastal region beginning 

 with New York and extending north and south that almost all the 

 plants matching Murray's plate and description are found. Still fur- 

 ther, Murray's reference to an olive in describing the fruits ("Capsula 

 ovalis, olivae magnitudinis") is very significant. The plants cited in 

 our foregoing list as representing true X. echinatum, display, more than 

 any other native species of Xanthium from Eastern North America, 

 an open, plump, ovoid appearance to the body of the bur in such a way 

 as to suggest an olive. 



Numerous authors, like Thellung, have confused X. echinatum with 

 the European X. riparium Lasch. All the European specimens of 

 X. riparium examined by us (about fifteen sheets) have shown burs 

 uniformly smaller, much narrower and with much smaller achenes. 

 It appears to us probable that no European botanist, after examining 

 several American specimens of X. echinatum, would hesitate to regard 

 X. riparium as distinct. 



The plant described by Rafinesque (loc. tit.) as X. maculatum, came 



1 Thellung had seen, for X. campestre.only an incorrectly determined specimen, 

 H. E. Brown 938. 



a Cf. Torr. and Gray (Fl. N. Amer. 2: 295. 1843), who referred to this plate as 

 "a good figure." But Thellung (loc. '/.), who clearly had a very incorrect con- 

 ception of Murray's species, called the plate very bad ("pessima"). 



