Skricocarpus. composite. 333 



Subtribe I. AsterinejB, DC. Heads heterogamous and radiate, or homogamous, never 

 diacious. Receptacle seldom chaffy. Anthers not caudate. Leaves almost always 

 alternate. 



CONSPECTUS OP THE DIVISIONS AND GENERA. 



Div, 1. ASTERE^. Heads heteTogamoos, radiate ; the rays white, purple or bhie ; the disk-flowers yellow, 

 but frequently changing to purple in fading. 



7. Sericocirpus. Pappus simple, unequal. Flowers of the ray and disk few. Involucre oblong, imbricated, cartilagi- 



nous. 



8. Aster. Pappus simple, copious. Rays numerous, in a single series. Involucre more or less imbricated. Receptacle 



alveolate. 



9. DiPLOPiFPUs. Pappus double ; the exterior short and setsiceous, or sqnamellate-subulate. Rays in a single series. 



Involucre imbricated. 



10, Erigeron. Pappus either simple or double ; the exterior setaceous-subulate, or squamellate. Rays very numerous, 



and often in two or more series. Scales of the involucre nearly equal, almost in a single series. Receptacle naked. 



Div. 2. CHRYSOCOMEjE. Heads either heterogamous and radiate, or homogamous and discoid; the 

 rays and disk-flowers yellow and unchanging. Receptacle never chaffy. 



11. SOLIDAGO. Rays few ; disk-flowers several. Pappus similar in the disk and ray, simple. Receptacle alveolate. 



18. Chrtsopsis. Pappus of the ray double, and dissimilar ; exterior pappus short, setose or chafl^y ; the inner capillary. 



Diy. 1. AsTERE.£, DC. Heads heterogamous, radiate; the rays while, purple or blue; disk-flotoers 

 yellow, but frequently changing to purple in fading. Receptacle not chaffy. 



7. SERICOCARPUS. Nees, Ast. p. 148 ; Endl. gen. 2310. SERICOCARPUS. 



Species of Aster, Linn, tf- others. 

 [ From the Greek, serikos, silky, and karpos, fruit ; the achenia being very silky .j 

 Heads 12 - 15-flowered ; the ray-flowers about 5 ; those of the disk tubular, fertile. Involucre 

 oblong or somewhat cylindrical ; the scales closely imbricated in several series, nerveless 

 or obscurely one-nerved, whitish and cartilaginous towards the base, the upper part herba- 

 ceous and often spreading or squarrose. Receptacle small, alveolate ; the alveoli toothed 

 or lacerate-ciliate. Rays oblong-linear. Appendages of the style (in the disk-flowers) 

 subulate. Achenia obpyramidal, short, densely silky. Pappus composed of simple, rigid, 

 rough bristles. — Perennial herbs, corymbose at the summit, with alternate entire or serrate 

 sessile leaves. Heads in crowded corymbs. Flowers of the ray white ; of the disk yellowish. 



1. SERICOCARPUS coNYzoiDES, Nees. Broad-lcaved Sericocarpus. 



Stem somewhat pubescent, slightly angular ; leaves ciliate, smooth underneath, veiny, 

 obscurely 3-nerved ; the upper ones oblong or lanceolate ; lowermost spatulate-oval, coarsely 

 serrate towards the apex, tapering into a margined petiole at the base ; involucre oblong- 

 turbinate , the scales squarrose at the tip ; rays rather short ; pappus ferruginous. — Nees, 



