CARDUACEAE. 305 



4-aiigled, embraced by the bractlets. Pappus of 2 awns or scales, sometimes 

 accompanied by smaller awns, all deciduous. — Fall. — Sunflower. 



Leaf-blades petioled or with petiole-like bases. 

 Main stem smooth and glabrous. 



Bracts of the involucre much surpassing the top of the disk. 



1. //. dccapetalus. 

 Bracts of the involucre about equalling the top of the 



disk. 2. H. strumosns. 



Mam stem pubescent. 



Leaf-blades prevailingly ovate or ovate-lanceolate. 3. H. tubcrosus. 



Leaf-blades ijrevailingly lanceolate. 



Leaves mostly alternate; blades narrowed at the 



base : achenes narrow, cuneate-oblong. 4. H. yUjantcns. 



Leaves mostly opposite : blades obtuse at the base : 



achenes broad, obovoid. 5. n. amUguus. 



Leaf-blades sessile and partly clasping. 6. H. divaricatus. 



1. H. decapetalus L. Stems 5-16 dm. tall, glabrous below the infioreseence: 

 leaf-blades membranous, ovate to oblong-lanceolate, 8-20 cm. long, coarsely 

 serrate: bracts of the involucres linear to linear-lanceolate, 1.5-2 cm. long: 

 ligules of the ray 2.5-3 cm. long: disk about 1.5 cm. broad. — Common, in 

 moist thickets and along streams. 



2. H. strumosus L. Stems 6-18 dm. tall, glabrous or nearly so to the in- 

 florescence: leaf-blades ovate to lanceolate or oblong-lanceolate, 8-20 cm. long, 

 whitish beneath: bracts of the involucre lanceolate to oblong-lanceolate, the 

 inner ones scarcely dilated: ligules of the ray 2.5-4 cm. long: disk 1.5-2 cm. 

 broad. — Common, on dry banks and in thickets. 



3. H. tuberosus L. Stems 6-30 dm. tall, scabrous to hirsute: leaf -blades 

 ovate to lanceolate, 8-20 cm. long, shaJlowly or coarsely toothed : bracts of the 

 involucres linear to linear-lanceolate, the inner 12-21 mm. long: ligules of the 

 ray 2.-5-4 cm. long: disk 15-20 mm. broad. — Common, in rich soil, waste places 

 and fence-rows. 



4. H. glganteus L. Stems 9-30 cm. long, scabrous and hispidulous at least 

 above: leaf -blades lanceolate to oblong-lanceolate or linear-lanceolate, .5-15 

 em. long, toothed or nearly entire : bracts of the involucre lanceolate or elliptic- 

 lanceolate, the inner 13-18 mm. long: ligules of the ray 1.5-2 cm. long: disk 

 10-15 mm. broad : achenes cuneate-oblong, 1.5-2 mm. wide. — Common, in low 

 grounds. — Jerusalem-artichoke. 



5. H. ambiguus (T. & G.) Britton. Similar to E. giganteus in habit, but less 

 harshly pubescent: leaves mostly opposite; blades lanceolate, rounded at the 

 base: bracts of the involucre attenuate, reflexed at maturity: achenes obovoid, 

 2.5-3 mm. wide. — S. Rare, in thickets near Pleasant Grove. — Schists. 



6. H. divaricatus L. Stems 3-12 dm. tall, commonly smooth and glabrous: 

 leaf-blades lanceolate or ovate-lanceolate, sessile or nearly so: bracts of the 

 involucre lanceolate or oblong-lanceolate, 8-10 mm. long: disk 10-15 mm. 

 broad. — N. S. Frequent, in thickets. — Sandstones and shales, schists. 



34. EIDAN Adans. Perennial rather coarse tall herbs. Leaves alter- 

 nate or opposite : blades usually toothed and decurrent. Heads several or 

 numerous. Involucre narrow: bracts few, spreading or recurving, becoming 

 lax. Eay-flowers few: ligules yellow or white, or wanting. Disk-corollas with 

 a f unnelf orm throat rather abruptly contracted into the shorter tube : lobes 

 lanceolate. Filaments slightly shorter than the anthers. Pappus of 2 more or 

 less spreading awns, accompanied by 2 or 3 smaller awns, or scales. 



1. R. altemifolia (L.) Britton. Plants 6-25 dm. tall: leaf -blades oblong or 

 elliptic, 9-30 cm. long: disk-corollas 5 mm. long: achene-body with ciliate 

 wings. — Common, in moist thickets and on roadsides. 

 Lancaster County Flora 20. 



