34 FIELD MUSEUM or NATURAL HISTORY BOTANY, VOL. IV. 



(Hb. N. Y.) ; Temescal, Oct., 1889, Edward L. Greene (Hb. Greene 19822 ; 

 Greene's only specimen of his X. californicum and by us regarded as 

 the type; matched most minutely by W. L. Jepson's plant from Oak- 

 land, see below) ; Amador County, Middle Fork, George Hansen 700 

 (Hb. Mo. 85389) ; Suisun Marsh, along railroad near Suisun, A. A. Heller 

 7550 (Hb. Gray; Hb. Mo. 85386; Hb. N. Y.); cultivated land, north of 

 Oroville, idem 12647 (Hb. Field 460600; Hb. Mo. 802978; atypical and 

 approaching X. italicum Mor.) ; Rio Vista, bank of Sacramento River, 

 Sept. 16, 1891, W. L. Jepson (Hb. Calif. 36799; this is a form interme- 

 diate between the types of X. acutum Greene and X. californicum 

 Greene, in Hb. Greene); Oakland, Oct. i, 1894, idem (Hb. Mo. 85387; 

 the exact form described by Greene as X. californicum and important 

 as coming from the range emphasized by him, "Middle California, 

 especially about San Francisco Bay"); near San Francisco, in 1866, 

 Dr. A. Kellogg (Hb. Gray); near Stockton, in 1888, J. A. Sanford (Hb. 

 Greene 19819; type of X. acutum Greene). 



Wallroth divided this species into two varieties, o. glandulosum and 

 ft. eglandulosum, according to the presence or absence of minute glands 

 upon the fruits and lower surfaces of the leaves. The var. glandulosum 

 was collected by Beyrich at Asheville [North Carolina] in 1833, while the 

 var. eglandulosum was collected by Poeppig in Pennsylvania, Sept., 1824. 

 We have not seen type material of var. glandulosum; of var. eglandu- 

 losum, however, we have seen the cotype specimen in the Bernhardi 

 Herbarium (Hb. Mo. 85594). But this shows clearly, under a lens with 

 a magnification of fourteen diameters, many minute glands, evidently 

 missing on the type or perhaps overlooked by Wallroth. Thus Wall- 

 roth's separation of the species into two varieties is seen to be without 

 real basis in fact. 



Among botanists there has been almost endless confusion between 

 X. pennsylvanicum and the species treated below as true X. italicum 

 Mor. Our own experience in the herbarium indicates these to be, with- 

 out question, distinct. In the field, our numerous observations during 

 the season of 1918 show that, where the two grow side by side, X. 

 italicum commonly displays a more compact mass of burs near the apex 

 of the stem and branches than does X. pennsylvanicum. This com- 

 pactness, added to the greater pubescence of the burs, often imparts to 

 X. italicum an appearance very unique. 



Of X. saccharatum Wallr., there is the cotype in Gray Herbarium. 

 This is plainly X. pennsylvanicum. We find a badly scrawled name 

 given for the locality to say "Bexar." Clearly the plant (Berlandier 

 1865} was collected at Bexar, Texas, and not in Mexico as some writers 

 have persisted in stating (although, to be sure, Texas had been a part 



