SOME WESTERN SPECIES OF XANTHIUM. 59 
Virginian plant for its type, if the species can be said to 
have, with Linnzus, any type at all. Miller's X. Canadense 
is perhaps as complex; but, as he defines no species at all, 
the name might well be treated as a nomen nudum ; and es- 
pecially in view of what, to me, is manifest, that it has been 
applied by different botanists to perhaps not less than a 
dozen distinct North American species. The X. Americanum 
of Walter and X. maculatum of Rafinesque are equally in- 
determinable, insomuch that the elder De Candolle, to get 
rid of so bad a lot, proposed a new name X. macrocarpum 
var. glabratum to cover all the North American members of 
this group known to him. In a monograph by Wallroth, 
published in 1842, that author seems to have found the dif- 
ficulties with the older North American species altogether 
insurmountable. He therefore rejects all the older names, 
assigning new ones to the five species which he makes out 
as belonging to our country. The identification of these 
will devolve upon him who shall undertake to disentangle 
eastern and southern Xanthia. At present I know nothing 
as to what his X. levigatum, pungens, Pennsylvanicum, van- 
thocarpum or oviforme are. Presumably, however, they all 
belong to the Atlantic slope of the continent. Little or 
nothing was known of this genus as represented west of the 
Mississippi in the year 1842. As all the following are from 
far-western regions, I shall, in naming them as new, incur 
small risk of becoming a manufacturer of synonyms. 
X. VARIANS. Upright, simple or sparingly branched, fruc- 
tiferous in all the axils almost from the base: stem very 
sparsely and minutely setose-hispid: leaves varying from 
lanceolate and serrate in the lowest to rhombic-ovate and 
broadly ovate-trigonous in the upper, these not lobed but 
doubly serrate-dentate, all tapering (though some abruptly) 
to the petiole, both surfaces scabrous: fruiting involucres 
oval, 8 to 10 lines long, densely prickly, the prickles half as 
long as the diameter of the body, slender conical, brownish- 
