294 



CAKDUACEAE. 



Stem and branches hirsute : involucres hemi- 

 spheric. 

 Cauline leaves, at least the lower ones, with 



toothed blades. 



Stem and branches glabrous, or inconspicuously pu- 

 bescent above. 

 Leaves with sharply serrate blades. 



Leaves abruptly contracted into broad petiole- 

 like bases, which are often dilated near the 

 stem. 



Leaves tapering to the base. 

 Leaves with entire blades, or sometimes with an 



occasional sharp tooth. 

 Blades of the cauline leaves with merely sessile or 



essentially sessile blades. 

 Ray-corollas with violet ligules : leaf-blades short 



and broad. 



Ray-corollas with white, or sometimes pink or pur- 

 plish, ligules. 



Flower-heads scattered : peduncles elongate, con- 

 spicuously scaly. 

 Flowers-heads racemose or paniculate : peduncles 



not copiously scaly. 

 Involucral bracts obtuse : stem, branches, and 



leaves, rough-pubescent. 



Involucral bracts acute or merely obtusish : 

 stem, branches, and leaves, glabrous or 

 softly pubescent. 



Flower-heads in secund racemes or panicles. 

 Blades of the cauline leaves oblong to 



lanceolate, serrate or dentate. 

 Blades of the cauline leaves linear to 

 linear-lanceolate, minutely hack- 

 toothed. 



Flower-heads not in definitely secund ra- 

 cemes or panicles. 



Cauline leaves with linear entire blades. 

 Cauline leaves with broader toothed 



blades. 

 Heads less than 16 mm. across the 



ligules. 

 Heads over 16 mm. across the 



ligules. 

 Ligules of the ray mostly white : 



leaf-blades thinnish. 

 Ligules of the ray bluish-violet : 

 leaf-blades firm. 



9. A. Novae- Angliae. 



10. A. puniceus. 



10. A. puniceus. 



11. A. prenanthoides. 



12. A. laevis. 



13. A. Radula. 



14. A. dumosus. 



15. A. multiflorus. 



16. A. lateriflorus. 



17. A. vimineus. 



18. A. ericoides. 



19. A. Tradescanti. 



20. A. paniculatus. 



21. A. salicifolius. 

 Stems tufted, 4-6 dm. tall, assurgent, flexuous, terete, 



1. A. divaricatus L. 



glabrate at maturity: leaf -blades thin, smoothishj slender-petioled, ovate-lan- 

 ceolate, closely and saliently dentate with sharp teeth, incurved-acuminate, the 

 basal sinus moderately large, broad and deep: leaves of the inflorescence 

 typically small, sessile, short, ovate-acute to short-oval, nearly entire: corymb 

 broad, flattish, repeatedly and widely forked, the slender branches long, 

 divergent: heads 18-25 mm. broad: young involucre short-cylindric ; bracts 

 broad, ciliate, the rounded or subtruncate tips with a broad green spot: ray- 

 flowers chiefly 6-9; ligules white, or rarely roseate or slightly crimson: disk 

 turning reddish-brown Common, in thickets and on hillsides. 



2. A. tenebrosus Burgess. Stems glabrate, striate, wide-branched: leaf -blades 

 large, very thin and smooth, broadly oblong and conspicuously cut with coarse 

 remote acuminate curvescent teeth, then abruptly long-acuminate and entire; 

 most leaves with a broad rounded sinus and slender petiole; those of the 

 inflorescence prolonged, lanceolate, subentire and sessile: inflorescence broadly 

 corymbose, often proliferously branched: outer involucral bracts green, acute, 

 elongate-triangular, the others linear, obtusish: rays long, usually 9-12: disk 

 pale-yellow, turning purplish-brown. Eesembles A. divaricatus, but is larger 

 and thinner in all its parts, and with a different leaf -form. N. Occasional, on 

 wooded hillsides. Sandstones and shales. 



3. A. Schreberi Nees. Stems 7-11 dm. tall, often purple-tinged, with elon- 

 gate internodes: radical leaves, usually in wide colonies; blades reniform-ovate 



