CAEDUACEAE. 287 



Base of the leaf-blade not broader than the rest 

 of the blade or gradually narrowed. 

 Leaf-blades linear, entire or shallowly and 



irregularly toothed. 3. E. hyssopifolium. 



Leaf-blades lanceolate, oblong, ovate, or oval, 



markedly toothed. 4. E. Torrcyanum. 



Base of the leaf-blade broadly rounded, cordate, 

 truncate, or broadly cuneate. 

 Leaf-blades crenate, crenate-serrate or cre- 

 nate-dentate : involucral bracts narrow, 

 acute, acuminate or apiculate. 

 Branches of the inflorescence alternate : 



leaf-blades coarsely few-toothed. 5. E. verhcnaefoUtnn. 



Branches of the inflorescence opposite : 

 leaf-blades more finely and evenly 

 toothed. 

 Leaf-blades about as broad as long, 



truncate or subcordate at the base. G. E. rotundifolium. 

 Leaf-blades manifestly longer than 

 broad, rounded or broadly cuneate at 

 the base. 7. E. pubescens. 



Leaf-blndes sharply serrate : involucral bracts 



broad, obtuse. 8. E. sessilifoUum. 



Leaf-blades connate-perfoliate : heads over 9-flowered. 9. E. perfoUatum. 

 Leaves whorled in 3's to 6's : blades relatively broad. 



Leaf-blades crenate, the teeth somewhat apiculate : co- 

 rollas about 5 mm. long. 10. E. trifoliattm. 

 Leaf-blades serrate : corollas about 7 mm. long. 11. E. purpureum. 



1. E. urticaefolium Eeichard. Stems 4-12 dm. tall, puberulent or glabrate: 

 leaf-blades thin, ovate or rarely ovate-lanceolate, 4-12 cm. long, acuminate, 

 coarsely serrate: bracts of the involucre linear, ciliolate at the apex, the inner 

 3-3.5 mm. long: corollas 3 mm. long: anthers longer than the filaments: achenes 

 2-2.5 mm. long. — Common, in woods and thickets. — White- snakeroot. 



2. E. aromaticum L. Stems 3-15 dm. tall, puberulent or minutely pubescent: 

 leaf-blades thickish, ovate to ovate-lanceolate, 2-10 cm. long, obtuse or acute, 

 crenate: bracts of the involucre linear, ciliate, the inner 4-4.5 mm. long: 

 corollas 4.5-5 cm. long, ciliate : achenes 2.5-3 mm. long. — M. S. Eare, in 

 thickets. — Qiiartzite, serpentine. 



3. E. hyssopifolium L. Stems 3-8 dm. tall, puberulent: leaf -blades linear, 

 2-6 cm. long, sometimes undulate : bracts of the involucre oblong to linear or 

 linear-lanceolate, ciliolate, mostly obtuse, the inner 5-5.5 mm. long: corollas 

 3.5-4 mm. long: achenes 2.5-3 mm. long. — Susquehanna valley. Occasional, 

 in thickets. — Schists. 



4. E. Torreyanum Short. Stems 4-12 dm. tall, finely pubescent: leaf -blades 

 broadly linear to oblong-lanceolate, coarsely serrate to laciniate: bracts of 

 the involucre mainly oblong to linear-oblong, ciliate, the inner 5-5.5 mm. long: 

 corollas 3 mm. long: achenes 3 mm. long. — Lower Susquehanna valley. Eare, 

 on wooded hillsides. — Schists. 



5. E. verbenaefolium Michx. Stems 6-12 dm. tall, finely pubescent: leaf- 

 blades ovate to lanceolate, 2-12 cm. long, serrate: bracts of the involucre 

 abruptly short-pointed, the inner mostly linear-oblong, 4-4.5 mm. long: achenes 

 about 2 mm. long. — M. S. Frequent, in moist grounds or swamps. — Schists, 

 quartsite. 



6. E. rotundifolium L. Stems 3-12 dm. tall, tomentulose: leaf -blades sub- 

 orbicular to orbicular-ovate, 2-4 cm. long, crenate or crenate-dentate : inter- 

 mediate bracts of the involucre acuminate, the inner ones 5.5-6 mm. long: 

 corollas about 3 mm. long: achenes fully 2 mm. long. — S. Occasional, in 

 swamps. — • Schists, 



7. E. pubescens Muhl. Stems 3-15 dm. tall, canescent-tomentulose: leaf- 

 blades ovate, 2-10 cm. long, serrate or incised-serrate: intermediate bracts of 

 the involucre abruptly pointed, the inner ones 5.5-6 mm. long: corollas about 

 3 mm. long : achenes 2-2.5 mm. long. — S. Common, in thickets. — Schists. 



