A. CANA. 151 



heads homogamous, mostly sessile in small glomemles, erect; involucre campanulate, 4 

 to 5 mm. high, 3 to 4 mm. broad, or considerably smaller in minor variation 4 in which 

 the heads are crowded and small; bracts 8 to 15, the outer orbicular or abruptly narrowed 

 above, the inner elliptic-spatulate, very obtuse, broadly scarious-margined, canescent 

 or tomentose; ray-flowers wanting; disk-flowers 6 to 15 or rarely 20, fertile, corolla tubu- 

 lar-funnelform, sharply 5-toothed, 2 to 3 mm. long, resinous-glandular; style-branches 

 disk-like at summit, the margins lacerate; achenes cylindric-turbinate, truncate and with 

 a slightly raised rim at summit, angled or with 4 or 5 evident ribs, granuliferous. 



On the plains and lower mountains, Saskatchewan to western Nebraska, New Mexico, 

 Utah, northeastern California, British Columbia, and Alberta. Type locality, on the 

 Missouri River. Collections: Saskatchewan Plains, Macoun 1011 (Gr); Indian Head, 

 Assiniboia, September 3, 1891, Spreadbough (US); Bozeman, Montana, September 3, 

 1902, W. W. Jones (DS, Gr, UC, US) ; Fort Bedford, North Dakota, Waldron 4I8 (NY) : 

 Centennial, southeastern Wyoming, Goodding 2118 (Gr, NY, UC, US); Sioux County, 

 Nebraska, June 17, 1897, Bates (Gr); Steamboat Springs, Routt County, Colorado, 

 Osterhout 2012 (Osterhout, NY, UC, type collection of A. cana viscidula Osterhout, minor 

 variation 1); Marshall Pass, Colorado, Baker 880 (Gr, NY, UC, US); Fish Lake, Utah, 

 Jones 5824 (NY, UC) ; Dulce, Rio Arriba County, New Mexico, Bailey 908 (US) ; 30 km. 

 north of Bridgeport, Mono County, California, Hall 11690 (UC); Little Truckee River, 

 California, September 1887, Sonne (UC); near Reno, Nevada, Kennedy 374- (UC); Lake 

 County, Oregon, Cusick 2737 in part (Gr, NY, UC, US) ; Caribou Forest, Idaho, Eggles- 

 ton 9975 (US). 



MINOR VARIATIONS AND SYNONYMS. 



1. Artemisia cana viscidula Osterhout, Bull. Torr. Club 27:507, 1900. — A state or condition of A. cana 

 in which the tomentum is light and obscured by a glutinous exudate, the herbage therefore greenish. Type 

 locality, Steamboat Springs, Routt County, Colorado. 



2. A. coLUMBiENSis Nuttall, Genera 2:142, 1818. — A. cana. In connection with the original description 

 Nuttall states that this "appears to be A. cana of Pursh," but later on he says that it is "certainly distinct 

 from the A. cana of Pursh" (Trans. Am. Phil. Soc, II, 7:399, 1841). No differentiating characters are given 

 other than that the leaves are all entire. A specimen in the herbarium of the Philadelphia Academy of Sciences 

 labeled as from the banks of the Missouri and Columbia Rivers and indicated by Nuttall as one of the types is 

 plainly A. cana. 



3. A. VISCIDULA Rydberg, Bull. Torr. Club 33:157, 1906. — Based upon A. cana viscidula Osterhout, which 

 see. Later reduced by Rydberg to A . cana (N. Am. Fl. 34 : 282, 1916) , a disposal with which the present authors 

 agree. 



4. An unnamed form with linear mostly entire leaves only about 1 mm. wide, on short, crowded twigs is 

 occasionally found in Wyoming: Evanston, Hcdl 10992; 40 km. west of Rawlins, Hall 10991; west of Laramie, 

 September 10, 1919, Clements. As far as observed these always grow in the proximity of plants of typical cana 

 and all show evident injury to the main stems, perhaps by browsing. This latter is believed to be responsible 

 for some of the changed characters. Except for the entire leaves, these plants are like A. tridentata bolanderi, 

 and even this distinction does not constantly hold, since occasional leaves are cleft, as shown in figure 22. The 

 twig illustrated is exceptional, since most of the leaves on this plant are entire. In one collection (10991) the 

 involucral bracts are almost exactly like those shown of bolanderi (fig. 23, a, b, c); in another (10992) the bracts 

 are like the last two drawings of genuine cana (fig. 23, /, g), but of smaller size, corresponding to the reduced size 

 of the heads. 



RELATIONSHIPS. 



In technical characters as well as in habit this species finds its nearest ally in A. tri- 

 dentata. Its whiter silvery pubescence and longer upper leaves serve to distinguish it in 

 the field. These leaves are typically entire and acuminate as contrasted with the 

 uniquely 3-toothed leaves on all but the upper twigs of tridentata. Moreover, each of 

 the subspecies of the latter has some individual peculiarity which serves to distinguish it. 

 In the case of tridentata typica, the one most likely to be confused with cana, this consists 

 in a reduced number of flowers, only 4 to 6 as contrasted with 6 to 20 in cana. The close- 



