132 COMPOSITiE. AsTKR. 



the margins scabrous ; the lower serrate ; scales of the involucre loosely im- 

 bricated, linear-subulate. Nees.— Willd. enum. 2. p. 887; Nees, Ast. p. 91 ; 

 DC. prodr. 5. p. 239. A. lanceolatus, Willd. spec. 3. p. 2050 ? (a species 

 of doubtful origin, perhaps not American), and of North American authors? 

 A. salicifolius, '^Darlingt. ! Jl. Cest. p. 467 ; not oi Ait. 1 A. sestivus, Ait. 1 

 Wiiid. 1 , - 



/3. stem diffusely branched ; the branches pubescent in lines, often elongated 

 and diverging; heads (variable but mostly rather large) racemose-scattered; 

 scales of the Involucre linear, acute, (rays blue or nearly white). — A. recur- 

 vatus, Nees, Ast. p. 93 ? A. Novi-Belgii var. minor, Boott ! in herb. Hook. 

 A. divergens (partly), Lindl. ! in herb. Hook. A. obliquus (partly), Lindl. 

 in herb. Hook. . 



y. heads (middle-sized) in dense or contracted axillary racemes which are 

 shorter than the cauline leaves ; otherwise as in /3. 



6. stem tall (4-6 feet high) erect; the branches hirsute or pubescent, o'ten 

 in lines; heads (pretty large) loosely racemose or somewhat paniculate 

 towards the extremity of the branchlets; rays blue. 



e. stem 1-2 feet high, pubescent in lines above ; heads numerous or crowd- 

 ed on the short branchlets, small; rays pale blue or bluish-white. 



Wet banks of streams and margins of swamps, Canada ! and nearly 

 throughout the United States ! a. d. & e. Common in the Northern and Mid- 

 dle States! /^. Ohio! Kentucky! &c. common, y. Ohio, Mr. Lea ! Aug.- 

 Oct. — A polymorphous and widely diffused species (not happily named 

 A. simplex), much resembling the A. salignus of Europe, as Nees remarks, 

 particularly the larger-flowered forms. Probably some species fouiided on 

 plants long cultivated in European gardens have been derived from it; and 

 perhaps A. obliquus, Nees, is among the number. Some states are, more- 

 over, very near our A. tenuifoUus y. bellidiflorus ; and our var. e. closely 

 approaches A. Tradescanti, but has larger heads, and broader as well as 

 more deeply serrated lower leaves. — The leaves are 1 to 4 inches long, 3-10 

 lines wide, tapering to an acuminate point, glabrous and smooth on both 

 sides, or the upper surface scabrous towards the margins, which are ciliolate- 

 scabrous; ^he lower serrate in the middle with small and sharp or mucronate 

 teeth, narrowed to the base, sessile or slightly clasping; the uppermost and 

 those of the branches mostly entire. Scales of the obovoid involucre more 

 or less unequal, loosely imbricated, narrow, acute; the tips often a little 

 spreading. Disk flowers at length turning brownish or purplish. Achenia 

 minutely pubescent. 



61. A. tenuifoUus (Linn.): nearly glabrous ; stem paniculate-compound, 

 or the branchlets and (rather small) heads often slightly racemose ; leaves 

 narrowly lanceolate or lanceolate-linear, mostly elongated, attenuate-acumi- 

 nate, the margin scabrous ; the lower ones usually sharply serrate in the 

 middle ; those of the branches and branchlets entire, attenuate, proportioned ; 

 scales of the hemispherical involucre numerous, linear or subulate-linear, 

 acute, closely imbricated, or the points somewliat spreading, the innermost 

 nearly as Ions as the disk; rays rather short. — Linn. spec. 2. p. 873 (at 

 least as to syn.'^Fluk.) ; Nees, Ast p. 119,- DC. ! j^rodr. 5. p. 245. A. Ameri- 

 canus Belvidere foliis, &c. PLuk. aim. p. 56, t. 78, /. 5. A. polyphyllus, 

 Willd. enum. 2. p. 888, fide Nees. A. junceus, Pursh, fl. 2. p. 557 ; {Ell. 

 sk. 2. p. 356 7) Nees, synops. p. 26, fide Nees. A. Tradescanti (partly), 

 Lindl. ! in herb. Hook. 



i3. ramosissimus : paniculately much branched ; the branches and branch- 

 lets rigid, somewhat erect, roughish-pubescent; leaves often scabrous ; scales 

 of theT involucre more closely imbricated and numerous, linear-subulate. — 

 A. tenuifoUus, {Linn. I. c. ?) Lindl. ! in herb. Hook. A. tenuifoUus y. Nees, 

 Ast. p. 120. 



y. bellidijiorus : paniculate-compound, rather strict ; the branchlets and 



