composite, (composite family.) 201 



lanceolate, acute, appressed. — Lincolnton, North Carolina, Curtis. — Stem pur- 



I>lc, 2° -3° high. Lower leaves 5' -6' long, 3" wide. Heads smaller than those 

 of the preceding. 



17. A. virgatus, Ell. Stem very smooth, straight, bearing the heads in 

 a single raceme at the summit of the long and slender branches ; leaves linear- 

 lanceolate, entire, rough on the margins, partly clasping, the lowest broader and 

 narrowed at the base; scales of the involucre lanceolate, acuminate; the outer 

 ones spreading. — Western districts of Georgia, and westward. — Stem 3° -4° 

 high. Lower leaves 3' -6' long; those of the branches small and numerous. 



18. A. COncinnus, Willd. Stem nearly smooth, somewhat loosely cor- 

 ymbose ; the branches virgate, dichotomous-panicnlate ; leaves lanceolate, 

 partly clasping, remotely and sharply serrate, with scabrous margins; those of 

 the branchlets oblong, entire; scales of the involucre linear, acute, closely imbri- 

 cated. (A. cyaneus ? Ell.)— Florida to North Carolina. — Stem 2° -3° high. 

 Achenia pubescent. 



# # # * Lower leaves large, cordate, on long petioles : heads middle-sized or small, 

 racemed or panicled : scales of the involucre somewhat membranaceous, with short 

 green tips : rays blue or violet. 



•*- Leaves entire, or nearly so. 



19. A. azureus, Lindl. Stem roughish, rigid, racemose-compound at the 

 summit, the branches slender ; leaves rigid, rough; the lowest ovate-lanceolate 

 or oblong ; the upper lanceolate or linear, sessile ; those of the branches subu- 

 late, appressed; scales of the obconical involucre closely imbricated, abruptly 

 acute. — Dry soil in the upper districts of Georgia and northward. — Stem 2° - 

 3° high. Rays bright blue. 



20. A. Shortii, Hook. Stem smoothish, slender, raccmose-paniclcd at the 

 summit; leaves nearly smooth, ovate-lanceolate, acute; those of the stem all on 

 slender petioles, and obtuse or cordate at the base, commonly entire ; those of 

 the branches oblong, sessile ; scales of the bell-shaped involucre linear, closely 

 imbricated, rather obtuse, shorter than the disk. — Mountains of Georgia and 

 westward. — Stem 2° -4° high. Bays violet-blue. 



21. A. undulatus, L. Pubescent; stem racemose-panicled above ; leaves 

 varying from lanceolate to broadly ovate, often wavy or slightly serrate on the 

 margins, roughish on the upper surface ; the lowest on long and slender petioles, 

 which are dilated and clasping at the base ; the upper on broadly winged peti- 

 oles, or sessile and clasping ; scales of the obovoid involucre linear, appressed , 

 acute. (A. diversifolius, A. sagittifolius, and A. scaber, Ell. ; the last with 

 smaller leaves, and very rough on both sides.) — Woods, common and very va- 

 riable. — Stem 2° -3° high. Heads small. Rays pale blue. 



22. A. asperulus, Torr. & Gray. Roughish; stem racemose-panicled 

 above, or simple ; lowest leaves oblong-ovate, obtuse or slightly cordate at the 

 base, sparingly serrate, on slender (not clasping) petioles ; the upper oblong, 

 narrowed at the base, sessile or on short winged petioles; those of the branches 

 minute; heads loosely racemed or panicled, small; scales of the hemispherical 

 involucre lanceolate, acute. — Dry gravelly soil, West Florida, Georgia, and 

 westward. — Stem 2° high. Rays pale blue. 



