Figure 62. — Flower head of 

 snakeweed (X. sarothraeJ 

 illustrating ray flowers 

 (arrow) . Specimen growing 

 at Wahsatch Station , Summit 

 Co.^ Utah. 



Distribution and habitat .- -This species is scattered throughout the Great Basin 

 and adjacent areas from southwestern Montana across Idaho to southeastern Oregon and 

 southward to northwestern New Mexico, Utah Nevada, and eastern California. In these 

 areas, spiny horsebrush occurs at elevations of 850 to 2,400 meters (2,800 to 7,900 

 feet) in alkali sinks, and in shadscale, sagebrush, creosote, pinyon- juniper , and 

 yellow pine vegetational types. 



Use . --Like Nuttall horsebrush, spiny horsebrush is of little direct use to animals 

 because of its growth habit. It does provide cover for smaller animals and is a useful 

 soil stabilizer where it grows. 



CHARACTERISTICS OF THE GENUS XANTHOCEPHALUM ° 

 (MATCHBRUSH, SNAKEWEED)" 



This genus consists of perennial herbs and low suf frutescent shrubs (subshrubs) 

 with woody roots, crowns, and stem bases. Its leaves are entire, linear to narrowly 

 oblanceolate, and usually sticky from resin exuded to the surfaces of both leaves and 

 young stems. 



Numerous small heads form in loose or crowed terminal clusters. Resinous, im- 

 bricated involucral bracts with thin membranous margins and green tips subtend each 

 head. A few yellow ray and disc flowers are both present (fig. 62). The ray flowers 

 are usually pistillate and fertile while the disc flowers are usually perfect and 

 fertile or sometimes staminate. Pappi of several small scales or awns are generally 

 present, at least on the disc flowers. Achenes are small, oblong or obovoid, and 

 pubescent. Blooming occurs from May to October. 



The basic chromosome number for Xanthooephalum is x = 4 (Solbrig 1971; Pinkava 

 and Keil 1977) . 



•"•^This genus has long been known as Gutierrezia (Ruff in 1974). 

 ■^^Other common names include matchweed, perennial snakeweed, broom snakeweed, 

 broomweed, resinweed, stinkweed, turpentine weed, and yellow top. 



63 



