STANDLEY TREES AND SHRUBS OF MEXICO 1495 



heads few to numerous, solitary at tips of stem and branches; involucre 5 to 8 

 mm. high, densely glandular-granular, strongly graduate, the phyllaries linear 

 or linear-lanceolate, spinulose-tipped, with usually appressed greenish tips; 

 rays numerous, pale yellow, the lamina about 6 mm. long; achenes densely silky. 

 "Hierba de vibora." 



This plant is sold in the markets of Coahuila as a blood purifier. 



27. Aplopappus junceus Greene, Bull. Calif. Acad. 1: 190. 1885. 

 Eriocarpum junceum Greene, Erythea 2: 108. 1894. 



Sideranthus viridis Rose & Standi. Contr. U. S. Nat. Herb. 16: 19 pi 15 

 1912. 



Sonora and northern Baja California. Southern California and Arizona; 

 type from San Diego County, California. 



Suffrutescent below, up to 1 meter high, the stems slender, finely glandular- 

 granular; lower leaves linear, about 2.5 cm. long, pinnatifid with few short lobes, 

 the others linear, entire or few-toothed, obtuse, spinulose-mucronate, about 8 

 mm. long, 1 mm. wide; heads as in the last species, the involucre 5 to 8 mm. 

 high. 



28. Aplopappus arenarius Benth. Bot. Voy. Sulph. 24. 1844. 

 Aplopappus arenarius incisifoUus I. M. Johnston, Proc. Calif. Acad. IV. 



12: 1190. 1924. 



? Aplopappus arenarius rossii I. M. Johnston, Proc. Calif. Acad. IV. 12: 1191. 

 1924. 



Southern Baja California; type from Cape San Lucas. 



Suflfruticose or herbaceous, low, spreading, densely pubescent all over with 

 mostly gland-tipped hairs; leaves cuneate to cuneate-obovate, 1 to (lowest) 3 cm. 

 long, 4 to 12 mm. wide, usually obtuse or rounded, denticulate to laciniate-lobed 

 with sometimes spinulose-tipped teeth; involucre larger than in the last two 

 species, about. 1 cm. high, the phyllaries densely glandular and with loose 

 herbaceous tips. 



25. CHRYSOTHAMNUS Nutt. Trans. Amer. Phil. Soc. n. ser. 7: 323. 1840. 



Shrubs or undershrubs; leaves alternate, narrow, entire; heads yellow, 

 corymbose-panicled, discoid and 5-flowered (in ours) ; involucre 3 to 5-seriate, 

 graduated, the dry, sometimes herbaceous-tipped phyllaries arranged in distinct 

 vertical rows; achenes slender, terete or angled; pappus of numerous soft or 

 stiffish, white or brownish-tinged, slender bristles. 



Plants of this genus are abundant and characteristic shrubs of the Rocky 

 Mountain region, where they are commonly known as "rabbit-brush." The 

 stems contain a' certain percentage of rubber, but probably too little to be of 

 commercial importance. 



Branches not tomentose. 



Involucre 9 to 12 mm. high; phyllaries acuminate; leaves linear or linear- 

 spatulate, flattish, not glandular-punctate 1. C. pulchellus. 



Involucre 6 to 7 mm. high; phyllaries obtuse; leaves involute-filiform, subterete, 



densely glandular-punctate 2. C. paniculatus. 



Branches densely tomentose 3. C. latisquameus. 



1. Chrysothamnus pulchellus (A. Gray) Greene, Erythea 3: 107. 1895. 



Linosyris pulchella A. Gray, PI. Wright. 1: 96. 1852. 



Bigelovia pulchella A. Gray, Proc. Amer. Acad. 8: 643. 1873. 



Chihuahua. Kansas to Utah, south to Texas and Arizona; type from western 

 Texas. 



Shrub 1 meter high or less, glabrous, white-barked; leaves cuspidate-apiculate, 

 1 to 2.5 cm. long, 1 to 2.5 mm. wide; phyllaries strongly keeled, with lanceolate 

 greenish tips; achenes glabrous; pappus stiflSsh, about 1.2 cm. long. 



