Erigeron. composite. 167 



often with minute setfe intermixed or forming an indistinct outer series, or 

 sometimes with a distinct and short, squamellate-subulate or setaceous (or 

 somewhat coroniform) exterior pappus ; the inner rarely wanting in the ray. 

 — Herbs, or rarely suffrutescent plants; with entire, toothed, or lobed leaves. 

 Heads solitary, corymbose, or paniculate. Rays white, blue, or purple. 



It appears to vxs impossible to effect generic divisions among these plants, by 

 characters derived froni the single or double series of rays, or from the simple or 

 double pappus, or by any combination of these. The characters of our sections, 

 or subgenera, exhibit the diversities which the North American species present in 

 these respects. As a whole, the genus is distinguislied from Diplopappus by the 

 very short and obtuse appendages of the style, the nearly simple involucre, and the 

 naked receptacle : the same characters also distinguish it from Aster ; but the Alpi- 

 genous'Asters almost connect the two genera. 



§ 1. Rays in several series, shorter than tJic involucre: pappus simple : ache- 

 nia 2-nerved : corolla of the disk inostly ^-toothed: annual or hiennial 

 herbs: heads very small, cylindrical. — C^jjotus, Nutt. 



1. E. Canadense (Linn.) : stem erect, hispid, or sometimes nearly gla- 

 brous, paniculately verv much branclicd above ; leaves lanceolate-linear, 

 mostly entire, hispidly ciliate ; heads small, very numerous, corymbose-pani- 

 culate or somewhat racemosely disposed on the branchlets ; rays (white) 

 scarcely longer than the pappus; achenia oblong, sparsely hispid. — Linn..' 

 spec. 2. p. 86.3 ; Ft. Dan. t. 292; Michx. ! fl. 2.^ p. 123 ; Nutt..' gen. 2. p. 

 148; Hook..' fl. Bor.-Am. 2. p. 20; Darlingt..' fl. Cest. p. 471; DC. ! . 



2nodr. 5. p. 289. E. pusillum, Nutt..' I. c. (a depauperate form.) Senecio 

 ciliatus, Wcdt. 



Fields and waste or open places, Canada! and Saskatchawan ! throughout 

 the United States! to Texas! and in Oregon ! Also apparently indigenous 

 to almost every part of the world, and naturalized in Europe. July-Oct. — 

 A common weed, very variable in size (from 5 inches to 5 feet) and mode of 

 growth. Involucre at first cylindrical, at length spreading. Ligule of the 

 ray many times shorter than the tube. Corolla of the disk (perhaps always ?) 

 4-toothed. Radical leaves often pinnately incised or lobed. — Horse-weed. 

 Butter-iceed. 



2. E. divaricatnw (Michx.) : decumbent, diffuse, and very much branched, 

 the branchlets fastigiate, strigose-hirsute and often somewhat hispid ; leaves 

 linear or subulate? heads small, loosely paniculate-corymbose; rays (purple) 

 not longer than the pappus; achenia oblong, aImo.st glabrous. — Michx.! fl. 2. 

 p. 123 ; Pursh ! fl. 2. p. 534 ; Null. I. c. ; DC. I. c. 



Throughout the Western States, from Illinois ! and Upper Missouri ! to 

 Louisiana ! along the Mis.sissippi ; in similar situations with the preceding, 

 flowering during the whole summer. — Plant rarely exceeding 6 inches iu 

 height, but very diffuse, at length spreadingout one or two feet in width. 



§ 2. Rays crowded or in two or more series, longer than the involucre : pap- 

 pus simple or sometimes with minute setce intermixed or forming an indis- 

 tinct external series: achenia 2-nerved: mostly perennial. — Euerigeron. 

 (Euerigeron & Trimorpha3a, DC. excl. spec.) 



* CcBspUose acaulescent {chief,y alpine) species : scapes bearing a single head : leaves 

 mostly 3-deft or divided : pistillate flmvers all ligvlafe. 



3. E. compositum (Pursh) : canescently hirsute ; leaves on long petioles, 

 1-3-ternately divided or parted ; the ultimate segments linear, obtuse ; scapes 



