Skricocarpds. composite. 333 



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

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

 alternate. 



CONSPECTUS OF THE DIVISIONS AND GENERA. 



Div. 1. ASTEREiE. Heads heterogamous, radiate ; the rays white, purple or blue ; the disk-flowers yellow, 

 but frequently changing to purple in fading. 



7. Sericocarpus. 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. DiPi.oPAPPus. Pappus double; the exterior short and setaceous, or squamellate-subulate. Rays in a single series. 



Involucre imbricated. 



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



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



Div. 2. CHRYSOCOME./E. Heads either heterogamous and radiate, or homogamous and discoid; the 

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



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



12. CuRYSOPsis. Pappus of the ray double, and dissimilar ; exterior pappus short, setose or chafly ; the inner capillary. 



Div. 1. AsTERE.a;, Z)C. Heads heterogamous, radiate; the rays while, purple or blue ; disk-flowers 

 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, <f- others. 

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



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-leaved Sericocarpus. 



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

 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, 



