DIVISION INTO SECTIONS. 161 



SO untrustworthy as to render the arrangement decidedly artificial. With the constant 

 increase in the number of species and of our knowledge concerning them, Gray's two 

 sections have become less and less satisfactory. Since the proposed sectional names 

 are not applicable under Chrysothamnus, an entirely new classification was advanced by 

 Hall in 1919 (Univ. Calif. Publ. Bot. 7:160). According to this latest arrangement, 

 the numerous forms are assembled into five natural groups, each of which is given a 

 formal section name. Four of these sections are adopted in the present paper, the 

 fifth, or Parryani, being now united with the Nauseosi, and the sequence is modified to 

 bring the more primitive sections at the beginning of the list. They are defined as 

 follows : 



Section 1. Punctati. Herbage resinous-punctate, the dots plainly showing as defi- 

 nite depressions; twigs brittle, glabrous, the bark at first green but soon changing to 

 brown; leaves terete; heads in open panicles; bracts of the involucre in vertical rows 

 which are fairly well defined, moderately keeled, obtuse and pointless, chartaceous, 

 either with or without an obscurely thickened greenish subapical spot; flowers 5 to 7; 

 style-appendage either shorter or longer than the stigmatic portion; achenes slightly 

 angled; densely pubescent. Species: terelifolius, paniculatus. 



Section 2. Typici. Herbage not resinou.s-punctate (somewhat punctate in one 

 species); twigs brittle, glabrous or only puberulent, the bark usually white; leaves ob- 

 lanceolate to narrowly linear but not terete; heads in rounded or flat-topped cymes, or 

 solitary and subracemose only in C. gramineus; bracts of the involucre in poorly defined 

 vertical rows, not strongly keeled, obtuse to acuminate but none continued into slender 

 herbaceous tips, more or less chartaceous, not rarely some of the outer with firmer and 

 indistinctly greenish apex; flowers 5 to 7; style-appendage either shorter than or much 

 exceeding the stigmatic portion; achenes slightly angled, pubescent or in two species 

 glabrous and 10-striate. Species: albidus, greenei, gramineus, vaseyi, viscidifiorus. 



Section 3. Pulchelli. Herbage not resinous-punctate; twigs brittle, glabrous or 

 puberulent, the bark greenish-white; leaves oblanceolate to revolute filiform; heads in 

 rounded c^mes; bracts of the involucre in very sharply defined vertical ranks, strongly 

 keeled, attenuate but never to an herbaceous tip, firmly chartaceous throughout; flowers 

 about 5; style-appendage shorter than or only slightly exceeding the stigmatic portion; 

 achenes nearly prismatic, not striate, glabrous or nearly so. Species: pulchellus, de- 

 pressus. 



Section 4. Nauseosi. Herbage not resinous-punctate; twigs flexible, densely 

 covered with a pannose tomentum, this more or less infiltrated with a resinous sub- 

 stance; leaves lanceolate or oblanceolate to linear-filiform but never truly terete, some- 

 times reduced to scales; heads in small panicles, racemes, or spikes or reduced to flat- 

 topped, rounded, or more elongated cymes or thyrses; bracts of the involucre in fairly 

 well defined vertical ranks, or these obscure, moderately to strongly keeled, obtuse to 

 acute, never with greenish apex but prolonged in one species into a slender tip, thin- 

 chartaceous throughout; flowers usually 5 to 15 but sometimes as many as 20; style- 

 appendage very slender and long exserted, nearly equaling or exceeding the stigmatic 

 portion; achenes slightly angled, pubescent or glabrous, not striate. Species: pyrami- 

 datus, parryi, nauseosus. 



