me aman — 
7 
Xanthium. 151 
branches erect, slender, nearly heads acute; pores unequal, 
irregular, small. 
A small species, three inches high, found at Oysterbay, 
on rocky bottoms, rare ; stem with few branches, and imper- 
fect ones, like knobs. Substance stupose. Branches round, 
alternate, small. Pores without any determinate shape. 
Arr. XIL. Memoir on the Xanthium maculatum, a New 
Species from the State of New-York, §c. by C.S. Rart- 
NESQUE, Esa. 
Pronrsn and Michaux mention only one species of American 
Xanthium, the X. strumarium, while there are three noticed 
in the catalogue of Dr. Muhlenberg, the above species, and the 
X orientale, and X. spinosum. ‘The first and the last are 
natives of Europe, and have been naturalized in the United 
States, with many other plants. The species called X. orientale 
by Dr. Muhlenberg, appears, however, to be a native ; but the X. 
orientale of Linneeus, is a native of Siberia, Japan, and the East 
Indies; and when plants are found to grow in such opposite 
quarters of the globe, a strong presumption arises that they 
are not identical species, which presumption has been con- 
firmed by experience in many instances, whenever the plants 
of both countries have been accurately examined. Decandolle, 
in the French Flora, (2d edition of 1815.) vol. 6. p. 356. 
describes, under the name of X. macrocarpon, a species found 
in France, and which he takes tobe the real X. orientale of 
Linnzeus, He has changed its name, because, he says, that it 
Snot certain that the X. orientale grows in Asia; or, if any 
Stows there, that it is identic with his species; which, how- 
ever, is really the X. orientale of Linueeus, Son, Lamark, and 
Gaertner. He adds, that he possesses in his herbarium, @ 
Species from Canada, different from his X. macrocarpon, which 
has been figured by Morison, on whose authority some authors 
have asserted that the X. orientale grew in Canada, mistaking 
his figure for that plant. 
