SOME WESTERN SPECIES OF XANTHIUM. 63 
. Known by a single specimen obtained at Stockton, Cali- 
fornia, by Mr. J. A. Sanford, in 1888. 
X. PALUSTRE. Erect, rather slender and simple, 2 or 3 
feet high, the stem green and glabrous, only scabrous above: 
strongly muricate-scabrous leaves, of broadly ovate outline, 
often indistinctly 3-lobed, the blade abruptly tapering to the 
long slender petiole, obtuse at apex, the margin coarsely 
dentate: fruiting involucres axillary and sessile in twos or 
threes, slightly obovate-oblong, densely echinate with re- 
markably short prickles, these hispid at base, and the body 
of the involucre either naked, or hispid with more or less 
numerous stout gland-tipped hairs; beaks short and stout, 
hispidulous, and with very short inflexed tip. 
Known only from the brackish marshes of Suisun Bay, 
middle California. An exceedingly well marked species, re- 
ferred to by me as an indigenous state of X. Canadense in 
the Flora Franciscana. 
X. ACEROSUM. Stems very stout and flexuous, strongly 
scabrous above: leaves broadly and subcordately ovate, 
obtuse, crenate-dentate, very scabrous and with rather copi- 
ous minute resin dots: fruiting involucres about 2 in each 
axil, one of them peduneulate or both subsessile, about 11 
inches long, very densely prickly, the prickles long and 
slender, hirsute or hispid to near the summit and with copi- 
ous short-stalked resin-glands intermixed with the hairs, 
the naked spinescent apex in about half of them perfectly 
straight and acerose, in the rest more or less curved or hooked; 
beaks slender-conical, little divergent, hispid up to the short 
strongly incurved tips. 
Known only from the valley of the Red River of the North, 
where it was collected by the writer, near Fargo, North Da- 
kota, 4 Sept., 1893. 
