288 CONTllIBUTIONS FROM THE NATIONAL HEEBAEIUM. 



32. VERBESINA L. 



1. Verbesina occidentalis (L.) Walt. Yellow crownbeard. 



Woods and fields, chiefly in alluvial soil; frequent. Aug.-Oct. Southeastern 

 U. S. {Phaethusa occidentalis Britton; V. siegesbeckia Michx.) 



A tall perennial with small heads of yellow flowers. In general appearance much 

 like Ridan alternifolius, but readily distinguished by the wingless achenes. 



33. COREOPSIS L. 



Plants hairy; stem leaves mostly simple and entire, narrowly lanceolate or oblanceo- 



late I.e. crassifolia- 



Plants glabrous; stem leaves all or nearly all compound. 

 Leaves petioled, divided into 3 or 5 lanceolate to linear-lanceolate leaflets, or the 



uppermost simple; plants 1-2 meters high; pappus none 2. C. tripteris. 



Leaves sessile, parted into numerous linear-filiform segments; plants usually less 

 than 60 cm. high; pappus of 2 short teeth 3. C. verticillata. 



Coreopsis tinctoria L. was reported by Ward as escaped in a few places but has not 

 been collected recently. It is an annual plant, native of the western U. S., common 

 in cultivation and frequently escaped. 



1. Coreopsis crassifolia Ait. 



Escaped in a few localities. Native of the southeastern states; often cultivated. 

 (C. lanceolata villosa Michx.) 



2. Coreopsis tripteris L. Tall tickseed. 

 Woods along the Potomac above Washington; frequent; also on Occoquan Creek 



and near Falls Church. July-Sept. Eastern U. S. 



8. Coreopsis verticillata L. Whorled tickseed. 



Thin woods and open fields; common. June-Oct. Eastern U. S. 



34. BIDENS L. 



Leaves lanceolate, simple, toothed. 

 Rays present; heads usually nodding in fruit. 



Rays much longer than the bracts; leaves finely and equally toothed, usually free 



at the base; achenes 6-9 mm. long 1. B. laevis. 



Rays mostly shorter than the bracts; leaves coarsely and unequally toothed, 



usually united at the base; achenes 5-6 mm. long 2. B. cernua. 



Rays none; heads erect. 

 Pappus awns upwardly barbed. Outer bracts 4 or 5, leaflike; leaves coarsely 



toothed; inner achenes less than 2 mm. broad 3. B. bidentoides. 



Pappus awns downwardly barbed. 

 Outei involucre of 4 or 5 short entire bracts; achenes 4-6 mm. long, angled. 



4. B. connata. 

 Outer involucre of 6-8 toothed leaflike bracts; achenes about 1 cm. long, flat. 



6. B. comosa. 

 Leaves pinnately parted or dissected, or the uppermost simple. 



Rays large and showy. Plants hairy; leaves with 5-7 linear-lanceolate, sharply 



toothed leaflets; achenes flat, more than 2 mm. broad 6. B. aristosa. 



Rays none or inconspicuous. 

 Leaves dissected into numerous small lobes; achenes linear, 4-angled. 



7. B. bipinnata. 

 Leaves composed of 3 or 5 large leaflets; achenes flat. 



Outer bracts 10-16; achenes brown, 3.3-4 mm. broad 8. B. viilgata. 



Outer bracts 4-8; achenes black. 

 Inner achenes less than 2 mm. broad; heads about 5 mm. high. 9. B. discoidea. 

 Inner achenes 2-3.3 mm. broad; heads 10-15 mm. long 10, B. frondosa. 



