1919J Hall: Chrysothamnus naiiseosus and Its Varieties 165 



Bracts of the iuvoliK-re abruptly pointed or some ouly acute. Far western. 



Tip of the bract short, erect 6. occidentalis 



Tip of the bract about 1 mm. long, very slemler, recurved.. -.16. renimiiwsu.s 

 Bracts obtuse to acute, not abruptly pointed. 

 Corolla-lobes glabrous. 



Involucre 6 to 9 mm. long, not sharply angled. 



Bracts ciliate, the outer often slightly hairy also on back, flat, thin, 



scarcely keeled 17. oreopJiihts 



Bracts not ciliate, all perfectly glabrous, concave, somewhat keeled. 

 Corolla 7 to 8.'.j mm. long; lobes under 2 mm.: twigs ami foliage 

 slender. 

 Lobes of corolla O.-j to 1 mm. long, rarely more : inflorescence 

 typically rounded to pyramidal. Rocky Mountain states. 



18. pinifoUus 

 Lobes of corolla 1 to 2 mm. long: inflorescence typically cylindric 



to pyramidal. Great Basin 19. coiislmiUs 



Corolla 8 to 10 mm. long; lobes 1.7 to 2.5 mm. long: twigs an<l 



foliage stouter. Southwestern 20. viridulus 



Involucre 9 to 10 mm. long, shai-ply 5-angled, the strongly keeled bracts. 



in very distinct vertical rows 21. mohavensis 



Corolladobes sparsely long-hairj' in the bud: shrub nearly leafless. 



22. junceus 



III. SYNOPSIS OF THE VARIETIES OF CHRYSOTHAMNUS 



NAUSEOSUS 



1. Chrysothamnus nauseosus (Pall.) Britt. {sensu strietii) 

 in Britt and Br., 111. FL, vol. 3, p. 326, 1898. 



Chrysocoma nauscusa Pall., in Pursh, Fl., vol. 2. p. .117, 1814. 

 Chri/sotlunrmus speciosus albicaulis Nutt., Trans. Am. Philos. Soc, ser. 2, 



vol. 7, p. 324, 1841. 

 Bigcloria graveolens albicaulis Gray, Proc. Am. Acad., vol. 8, p. 64.j, 1873. 



Shrub 5 to 10 dm. hig-h, with numerous erect or ascending- twigs, 

 leafy to the top, permanently white-tomentose throughout ; twigs not 

 evidently striate : leaves narrowly linear, 3 to 6 cm. long, 0.5 to 1.5 

 mm. wide : inflorescence a rather loose round-topped cyme : involucre 

 7 to 8 mm. high ; bracts mostly acute, plainly keeled, in 5 distinct 

 vertical ranks, white-woolly but not ciliate: corolla 7.5 to 9 mm. long; 

 tube perhaps always cobwebby with long weak liairs; lobes lanceolate, 

 1 to 2 mm. long. 



This type form of the species is much less common than numy of 

 its varieties. It occurs from Utah to Oregon and ])r()bal)ly north to 

 British Columbia and J\Iontana, inhabiting well draiiK^l soil with 

 little or no alkali. In the typical form, as understood by the writer, 

 the leaves are very narrow and, like the twigs, are entirely covered 

 with a white flocculent tomentum, while the corolla-tube is conspicu- 



