Art. XII. Memoir on the Xanthium maculatum, a New Species from the State of New-York, &c.
Art. XII. Memoir on the Xanthium maculatum, a New Species from the State of New-York, &c. by C. S. Rafinesque, Esq.
Pursh 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 Linnæus, 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 confirmed by experience in many instances, whenever the plants of both countries have been accurately examined. Decandolle, in the French Flora, (2d edit, of 1815.) vol. 6. p. 356, describes, under the name of X. macrocarpon, a species found in France, and which he takes to be the real X. orientale of Linnæus. He has changed its name, because, he says, that it is not certain that the X. orientale grows in Asia; or, if any grows there, that it is identic with his species; which, however, is really the X. orientale of Linnæus, Son, Lamark, and Gaertner. He adds, that he possesses in his herbarium, a 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.
From the above statement, it appears that much obscurity and difficulty arises in botany, when errors creep into the distinction of species: to detect those errors, and to ascertain the synonyme of obscure species, is not one of the least useful botanical labours. Having found, last year and this year, in the neighbourhood of New-York, a species of Xanthium different from any described by the authors, and intermediate between the X. strumarium and X. orientale of Linnæus, I presume that it may be the X. orientale of Muhlenberg, Leconte, and Morison, and the Xanthium of Canada, mentioned by Decandolle, Dumont, &c. I have given to it the name of X. maculatum, since the stem is spotted like the Conium maculatum. None of those authors having described it, I suppose that its description will be acceptable, and will serve to fix this new species among the American botanists.
Therefore it will appear, that the X. orientale, which had been considered as a native of Asia, Europe, and America, is composed of at least three species; the European species, which has been called X. macrocarpon by Decandolle, the American species, which I have called X. maculatum, and the Asiatic species, to which the name of X. orientale ought to remain; but which ought to be better described, and more fully distinguished from the X. macrocarpon by those who may chance to meet with it. I even suspect that many species grow in Asia, since that of Ceylon may be different from the Chinese and Siberian species.
Xanthium Maculatum.
Definition. Stem flexuous, round, rough, spotted with black; leaves long-petiolate, cuneate-reniform, nearly trilobe, sinuate-toothed, obtuse, rough, and thick; fruits elliptic, obtuse muricate; thorns rough.
Description. The root is annual, thick, and white. The stem rises from one to two feet; it is upright, without thorns, very thick, and with few branches; it is covered with oblong, black, and rough spots. The leaves are few, but large, with very long petiols; they are nearly reniform, with an acute base, and have three nerves; the teeth are unequal, large, and obtuse. The flowers and fruits are disposed as in X. strumarium; but the fruits are generally solitary; they are half an inch long, nearly cylindrical obtuse, with the two beaks scarcely perceptible and bent in, covered with short, thick, and rough thorns, rather soft, and not uncinate. The whole plant has a peculiar smell, not unpleasant, somewhat between the camphorate and gravulent odour, but weaker than in Conysa camphorata, &c.
History. This plant grows on Long-Island, near the seashore and marshes. I have found it common near Bath, on the downs, and in New-Jersey, near Bergen, and Powles Hook, on the margin of marshy meadows. According to Dr. Mulenberg, it grows also in Pennsylvania; Messrs. Torrey and Leconte found it on the island of New-York; and by Morison and Decandolle's account, it is found as far north as Canada. It blossoms in August and September, but the fruits remain on the plant till the severe frosts of December.