104 GENUS AKTEMISIA. 



ECOLOGY AND USES. 

 Artemisia klotzschiana is an annual with taproot, which forms clans in the desert 

 plains grassland at high altitudes in Mexico. So far as known, no use is made of this 

 species. 



15. ARTEMISIA BIGELOVI Gray, Pacif. R. R. Rep. 4:110, 1857. Plate 9. Flat 

 Sagebrush. 



A low shrub, commonly 2 to 4 dm. high, the odor faint, pleasant, not pungent; stems 

 many, spreading below, the numerous flowering branches slender and erect, the bark 

 apparently sheathing on the old parts, the twigs densely silvery-canescent, not striate; 

 principal leaves sessile by a narrow base or apparently petioled, linear-cuneate, 1 to 2 

 cm. long, 2 to 4 mm. wide, sharply 3-toothed at the truncate apex or many entire, silvery- 

 canescent; upper leaves linear-elliptic or linear-cuneate, mostly entire, acute or slightly 

 obtuse, silvery-canescent; inflorescence an elongated narrow panicle with short recurved 

 branches, sometimes nearly simple and spike-like, 8 to 20 cm. long, 1 to 4 cm. broad; 

 heads heterogamous, or rarely homogamous on the same plant by reduction of the ray- 

 flowers, sessile, several in each short recurved cluster; involucre turbinate, 2.5 to 3.5 mm. 

 high, 2 to 2.5 mm. broad; bracts 8 to 12, the outer ones ovate, thick, and only half as long 

 as the inner ones, these oblong and obtuse, all densely short-tomentose, the margins 

 scarious; ray-flower usually solitary, sometimes 2, or wanting, corolla cylindric, 1 to 1.5 

 mm. long, narrowed above, obscurely toothed; disk-flowers 1 to 3 (usually 2), fertile, 

 corolla broad-funnelform, 5-toothed, 2 to 3 mm. long, glabrous; style-branches of 

 ray-flowers 2-cleft, exserted, of disk-flowers 2-cleft, the branches erose-truncate, included; 

 achenes of both ray and disk ellipsoid, about 5-ribbed, glabrous. 



Southern Rocky Mountains, from southern Colorado and southeastern Utah to 

 northwestern Texas and western Arizona. Type locality, rocks and canons on the 

 Upper Canadian, Texas. Collections: Bluffs near Pueblo, Colorado, September, 1873, 

 Greene (Gr) ; Soda Springs Ledge and Frank's Ranch, Cafion City, Colorado, Brandegee 

 996 (UC) ; southeastern Utah, Rydberg and Garrett 9876 and 9891 (NY, UC) ; type collec- 

 tion, 1853-54, Bigelow (Gr, NY "Rocky Dell, September 18, western border of Texas," 

 according to label in Torrey Herb.) ; White Mountains, New Mexico, Wooton 502 (NY) ; 

 Burro Mountains, New Mexico, Rushy 232, in part (UC) ; near Farmington, northwestern 

 New Mexico, Hall III4I (UC); Navajo Indian Reservation, Arizona, Standley 7355 

 (NY, type collection of A. petrophila Wooton and Standley, minor variation 1); Billings, 

 Arizona, Jones 4571 (US); Grand Canon, Arizona, Hall 11187 (CI). 



SYNONYM. 



1. Artemisia petrophila Wooton and Standley, Contr. U. S. Nat. Herb. 16:193, 1913. — Described as 

 having homogamous heads, but in the type specimens the flowers are too immature for a positive determination 

 of this point. In every other respect the specimens are exactly like A. bigelovi, which apparently was over- 

 looked when the original diagnosis was prepared. The type came from near Farmington, New Mexico, where 

 typical bigelovi is plentiful, especially on the low hills towards the south. 



RELATIONSHIPS. 



The habit, general appearance and vegetative characters of this species are so nearly 

 those of A. tridentata that it is often so labeled in herbaria, but the presence of marginal 

 flowers plainly different from those of the disk assign it on technical characters to another 

 section of the genus, namely Abrotanum. The total number of flowers in the head is 

 greatly reduced. The number of ray-flowers is never more than 2, usually 1, and some- 

 times none. This last condition, if constant, would assign the species to the section 

 Seriphidium, but in no case has a plant been found in which more than a small percentage 

 of the heads were without ray-flowers. It may therefore be accepted as a highly modified 

 member of Abrotanum, although not approached by any other species of this section. 



