CARDUACEAE. 293 



pendages lanceolate. Achenes flattened, 1-nerved. Pappus of numerous sca- 

 brous bristles. Sum. WHITE-TOPPED ASTER. 



Leaf-blades entire, those of the cauline leaves narrow : inner involucral bracts 

 obtuse. i. s. Unifolius. 



Leaf -blades toothed, those of the cauline leaves broad : inner 



involucral bracts acute. 2. 8. asteroides. 



1. S. linifolius (L.) B.S.P. Stems glabrous or nearly so, 2-7 dm. tall: blades 

 of the upper leaves linear, 2-6 cm. long : involucres 4-6 mm. long ; inner bracts 

 often erose at the green tips: disk-corollas 4-5 mm. long: ligules 5-6 mm. 

 long: pappus whitish. S. Occasional, on dry banks. Schists. 



2. S. asteroides (L) B.S.P. Stems pubescent, 3-8 dm. tall: blades of the 

 upper leaves ovate, oblong-ovate, or lanceolate, 1.5-4 cm. long: involucres 6-9 

 mm. long; inner bracts broadly linear, rough-edged above: disk-corollas 5-6 

 mm. long : ligules whitish, 6-8 mm. long : pappus brownish. Common, in 

 woods and thickets. 



14. ASTER [Tourn.] L. Perennial, or rarely annual, branching caulescent 

 herbs. Leaves alternate : blades narrow or broad, entire or toothed, those of 

 the rootstock, base of the stem and upper parts of the plant often very differ- 

 ent. Radical leaves often appear from rootstocks remote from the flowering 

 plant. Heads radiate, in corymbs, racemes or panicles, or rarely solitary. 

 Involucres hemispheric, campanulate, cylindric, or turbinate: bracts in several 

 series, with erect, spreading or recurved tips. Eay-flowers pistillate, with 

 white, pink, purple, blue, or violet ligules. Disk-flowers perfect: corollas 

 yellow, becoming red, brown, or purple: lobes 5, broad. Achenes slightly 

 flattened, nerved or ribbed. Pappus of numerous bristles in one, or rarely two, 

 series. ASTER. 



Blades of the basal and lower cauline leaves relatively broad, of an ovate or cordate 

 type, and with long petioles, the upper cauline essentially similar, but shorter- 

 petioled or even sessile. 

 Upper cauline leaves various, but the blades not cordate-clasping ; petioles of the 



lower leaves not dilated-clasping. 

 Ray-corollas with white, pink, or violet ligules. 



Ligules white or occasionally pinkish, usually 2-toothed : pubescence not 



glandular. 

 Involucres not cylindric ; bracts broadly obtuse or rounded at the apex : 



basal leaves few, with small blades, or wanting. 

 Blades of most of the leaves of an ovate-lanceolate type ; blades 



of the branch-leaves mostly short. 1. A. divaricatus. 



Blades of most of the leaves of an oblong- 

 lanceolate type ; blades of the branch- 

 leaves elongate. 2. A. tenebrosus. 

 Involucres cylindric ; bracts tapering to the 

 blunt apex : basal leaves numerous, with 

 large blades. 3. A. Schreberi. 

 Ligules violet, usually 3-toothed : pubescence 



glandular. 4. A. macropliyllus. 



Ray-corollas with blue or purple ligules. 5. A. cordifolius. 



Upper cauline leaves with clasping blades or clasping 



dilated petioles. 6. A. undulatus, 



Blades of the basal and lower cauline leaves relatively nar- 

 row, and with more or less contracted petiole-like 

 bases, the upper cauline with sessile or clasping blades. 

 Blades of the cauline leaves clasping by auriculate-cor- 



date bases. 

 Stem and branches conspicuously pubescent, often 



rough-pubescent, 

 luline le! 



Cauline leaves with entire blades. 



Stem and branches rough-pubescent : involucres 



campanulate. 

 Leaves rough-pubescent : stem widely 



branched above. 7. A. patens. 



Leaves soft-pubescent : stem narrowly 



branched above. 8. A. phlogifolius. 



