face, smooth on outer face, those of the outer pistillate flowers with a loose 

 membranous coat which is expanded on the margins and extends over the back, 

 those of the central flowers with a narrow membranous margin; pappus wanting. 



In wet saline soils and marshy situations, often almost aquatic, in Ariz. (Mohave 

 and Yuma cos.); weed introd. from S. Afr. 



43. Artemisia L. Wormwood. Sagebrush 



A genus of a few hundred species in the cooler, drier parts of the world. The 

 plants are wind-pollinated and have toxic, allergenic pollen. The beverage absinthe 

 is made by steeping the leaves of A. absinthium L. in alcohol. Tarragon, an herb 

 used in cooking, is the herbage of A. Dracunculus L. The over-abundant "sage- 

 brush" of the western plains is A . tridentata Nutt. Most of our species afford some 

 low-quality forage for livestock, but only one is a wetland plant. 



1. Artemisia biennis Willd. 



Coarse essentially inodorous glabrous annual or biennial to about 3 m. tall; 

 leaves alternate, 5-15 cm. long, pinnatisect almost to the midrib into several 

 narrow lobes that are usually again sharply toothed or with the lower bipinnatifid; 

 inflorescence dense, spikelike or of several spiciform branches; heads numerous, 

 crowded, urceolate, scarcely pedunculate; involucre glabrous, 2-3 mm. high; flowers 

 all fertile, the outer pistillate; receptacle glabrous; phyllaries with very broad 

 scarious margins; achenes ellipsoid, 4- to 5-nerved, glabrous. 



Edge of marshes, stream banks, river beds and waste places generally, in N.M. 

 (Rio Arriba, San Juan and San Miguel cos.) and Ariz. (Coconino and Pinal cos.), 

 June-Sept.; Can. to N.J., Ky., Mo., N.M., Ariz, and Calif., where native, else- 

 where naturalized. 



44. Arnica L. 



About 35 species of circumboreal distribution; most highly developed in western 

 North America. 



1. Arnica Chamissonis Less. 



Perennial from long nearly naked rhizomes; stems solitary, 2-10 dm. tall; 

 herbage variously pubescent but not silvery-tomentose nor pilose, becoming some- 

 what glandular above; leaves simple, opposite; cauline leaves mostly in 5 to 10 

 pairs, not much reduced upwards, lanceolate to oblanceolate, sessile or with 

 the lowermost connate-petiolate, slightly toothed to entire, 5-30 cm. long, mostly 

 1-4 cm. wide, rarely more; heads usually several, campanulate to hemispheric; 

 involucre mostly 8-12 mm. high, its bracts obtuse or merely acutish and bearing 

 an apical or internally subapical tuft of white hairs; rays commonly about 13, 

 usually pale, 1.5-2 cm. long; achenes shortly hairy and glandular to subglabrous; 

 pappus tawny or whitish, barbellate to subplumose. A. foliosa Nutt. 



In wet meadows, alluvial soils, in wet soil along streams and about lakes, in 

 N.M. (Rio Arriba and Taos cos.) and Ariz. (Coconino Co.), July-Sept.; Alas, 

 to N.M., Ariz, and Calif. 



45. Senecio L. Groundsel. Ragwort. Squaw-weed 



Herbs or subshrubs; leaves alternate, often pinnatifid; involucre usually campanu- 

 late or obconic-campanulate (or urceolate at anthesis); phyllaries usually in 2 size- 

 classes; longer (inner) phyllaries 12 to 25, equal in length, in a double row, linear, 

 often acute, with a herbaceous median area and usually thin margins; outer 

 phyllaries much shorter, subulate-setaceous, forming a calyculum or in many 

 species entirely absent; receptacle slightly convex, essentially naked; ray flowers 

 present, pistillate, fertile; rays linear or elliptic-linear, yellow, terminally 3-toothed; 



1689 



