100 COMPOSITE. DiETERIA. 



* Corolla of the disk very narroiv, not dilated at the summit : appendages of the style 

 subidate-filiform. 



1. D. sessilijiora (Nutt.) : viscidly pubescent; stems simple; heads spi- 

 cate-racemose, often crowded ; leaves linear or somewhat lanceolate, incisely 

 spinulose-toothed ; rays (12-15) ochroleucous. — Nutt. ! in trans. Amer. phil. 

 soc. {n. ser.) 7. p. 301. 



Denudated j)]ains of the Rocky Mountains and Oregon, Nvtiall! — Stems 

 about a foot high, mostly simi)le, the base and lower leaves n)inuiely canes- 

 cent ; the u])per ])ortion, involucre, &c. viscid. Heads rather smaller than 

 the following, scarcely a third of an inch in diameter, obovate or lurbinaie, 

 disposed in a close or crowded raceme or spike. Achenia, as in the oiher 

 species of this division, narrow, canesceutly pubescent. — Very nearly allied 

 to the following species. 



2. D. viscosa (Nutt.) : pulverulently pubescent and viscid ; stems simple, 

 racemosely branched or soiuewhat corymbose; leaves linear, acute or acumi- 

 nate, incisely spinulose-toothed : rays (18-20) purple. — Nvtt. ! I. c. 



With the preceding, particularly near Scoit's Bluff" on the Platte, Nut- 

 talL! — " Stem simple, oiten very viscid, and exhaling the strong heavy scent 

 of Aster graveolens or Gnaphalium Americanum. Leaves sometimes near- 

 ly pinnatitid or runcinate." Nutt. — Scales of the turbinate involucre very 

 numerous, linear, rigid, with short squarrose-recurved tips. 



3. I), divaricata (Nutt.): minutely canescent, not glandular or viscid; 

 stem racemose or racemose-comj)ound; the branches divaricate; radical and 

 lower leaves lanceolate or somewhat spatulate, strongly sjnnulose-looihed ; 

 the upper linear, small, often nearly entire ; rays (12-16) short, pale blue or 

 purple. — ISutt. ! i. c. 



Denudated plains of the Rocky Mountains and Oregon, common, Nuttall! 

 — About a foot higli; branches rather naked, with small leaves, spreading out 

 into a compound corymb. Papjjus fulvous or white. Nutt. — The heads 

 are about the size of the preceding, apparently more broadly obo\()id or al- 

 most hemis|)herical ; with rather broader, I'ewer, and less acute, perbaps less 

 rigid, canescently puberulent (but not glaixlular or viscid) scales. The rays, 

 as in the preceding, are not much longer than the disk. — These species are 

 so nearly related that they may berealter be found to pass into each other. 



4. D. incana: perennial? minutely canescent throughout with a very 

 short soft pubescence; stem stout, racemosely branched ; the branches often 

 elongated and corymbose, terminated by single large heads ; leaves linear, 

 mucronulaie, entire, or frequently with a few laciniale mucronate teeih near 

 the base; involucre obovoid-hemispherical ; the linear slightly glandular 

 scales imbricated in numerous series, with very acute S(]uarro.se tips; rays 

 (about 30) large, bright violet; achenia narrow, canescent. — Diploj)a|)pus 

 incanus, Lindi. ! hut. rcg. t. 1693 ; Hook. ! hot. mag. t. 3382 ; DC. ! prodr. 

 6. p. 278. 



California, Douglas! (probably from the interior.) — Stem stout, 1-2 feet 

 high, apparently a little woody at the base : the branches simple or some- 

 what branclied, ascending, racemose, becoming corymbose at the summit. 

 Leaves 1—2 inches long, closely sessile or slightly clasping, about 2 lines 

 ■wide ; the lower obtuse, but mucronulate, ofien presenting 1 to 3 or 4 slender 

 divaricate and mucronate teeth on each side near the base. Heads in the 

 wild plant about two-thirds of an inch, in the cultivated nearly an inch, in 

 diameter, without including the numerous and large broadly linear rays. — 

 This is a genuine species of Mr. Nuttall's Dieteria, and the most showy 

 of the genus. The late Mr. Douglas alone seems to have met with it. 

 The cultivated specimens are less canescent, the branches more elonga- 



