A. RIGIDA. 153 



USES. 



The principal use of this sagebrush is as a browse shrub, especially for sheep. Accord- 

 ing to experts in grazing it is very important throughout most of its range and is eaten 

 quite extensively when other feed is scarce. In eastern California, where commonly 

 known as "white sagebrush," it is reported as a good browse shrub, even for horses and 

 cattle. 



Together with A. tridentata, it furnishes settlers and campers with fuel and shelter 

 and is much used for these purposes by the Indians, especially in regions where trees are 

 scarce. In England, it is cultivated to a limited extent as an ornamental, because of its 

 silvery leaves and stems. Penally, its importance both as a cause and a remedy for hay- 

 fever is perhaps no less than that of A. tridentata in proportion to its relative abundance. 



27. ARTEMISIA RIGIDA (Nuttall) Gray, Proc. Am. Acad. 19:49, 1883. Plate 22. 



Stiff Sagebrush. 



A low shrub, 4 dm. or less high, with pungent odor; stems thick and rigid, much 

 branched from near the base, the branches spreading or erect, forming rounded clumps, 

 clothed with a dark fibrous bark, the very short twigs not striate but canescent or gla- 

 brate and then yellowish; principal leaves sessile, spatulate in outline but with narrowly 

 linear base, 1.5 to 4 cm. long, 1 mm. wide below the lobes, parted or cleft from the summit 

 into 3 to 5 narrowly linear lobes, silvery-canescent on both sides; upper leaves similar and 

 only slightly reduced, sometimes entire, all longer than the heads; inflorescence a leafy 

 spike, 2 to 15 cm. long, less than 1 cm. broad exclusive of leaves; heads homogamous, 

 sessile and solitary in the axils or the upper ones somewhat glomerate, erect; involucre 

 campanulate, 4 to 5 mm. high, 2.5 to 3.5 mm. broad; bracts 12 to 26, the short outer ones 

 orbicular to elliptic and acute, the inner elliptic or spatulate and very obtuse, with a 

 white-scarious margin, all canescently tomentulose; ray-flowers wanting; disk-flowers 5 

 to 15, fertile, corolla funnelform, deeply and acutely 5-toothed, 2 to 2.8 mm. long, 

 glandular at least on the tube, often reddish; style-branches oblong, truncate, erose 

 across summit; achenes somewhat prismatic, 4- or 5-angled or with 4 or 5 ribs, glabrous. 

 {A. trifida rigida Nuttall, Trans. Am. Phil. Soc. II, 7:398, 1841.) 



On rocky ridges and plains, western Montana to eastern Washington and Oregon. 

 Type locality, plains of Lewis (Snake) River. Collections: Wild Horse Island, Flathead 

 Lake, Montana, Jones (according to Jones, Bull. Univ. Mont. 61:48, 1910); type collec- 

 tion, Nuttall (Or); Seven Devils Mountains, Washington County, Idaho, September 9, 

 1899, Jones (US); Yakima region, Washington, 1882, Brandegee; bluffs of Snake River, 

 above Wawawai, Washington, Piper 3814. (Gr, NY); eastern Oregon, Cusick 2504 (Gr, 

 UC, NY, US); east of The Dalles, Oregon, September 25, 1919, Hall (CI); south rim of 

 the Grande Ronde Valley, Union County, Oregon, Eggleston 13664 (US). 



RELATIONSHIPS. 



This is apparently an offshoot from the tridentata group of species, but because of 

 the absence of connecting forms its exact phylogeny is difficult to determine. In many 

 respects it suggests A. tridentata trifida, especially in its reduced stature, silvery pubes- 

 cence, and cut of leaf. The achenes are essentially prismatic and 4-angled as in other 

 members of this group. The reduction in size and inflorescence that is so evident in 

 trifida is here carried to its extreme, the plants being very low and the inflorescence 

 narrowed to a leafy spike. These traits suggest a direct derivation from trifida, and this 

 is not at all improbable. In addition to the reductions mentioned, rigida differs in its 

 elongated upper leaves, each with a head in its axil, in the more silvery pubescence, in 

 details of habit, and in its adaptation to less favorable soil and climatic conditions. It 

 is not a successful competitor with other shrubby Artemisias, as is indicated by its 



