340 COMPOvSITAE 



to Va., west to Minn, and Mich. Also on Pacific coast. Nat. from Eu. 

 — Pennsylvania : Phii<adbi<phia ; Monroe, Tobyhanna ; Fk.anki,in. 



6. Senecio sylvatious L. Wood Groundsei,. (Man. p. 1029 ; I. F. 

 f. 40S2-) In waste places, N. S. and Prince Edward Island. Also on the 

 coast of Calif, and B. C. Nat. or adv. from 'Em.— Pennsylvania : Phii,a- 

 DEI,PHIA, ballast. 



7. Senecio viscosus I,. Fetid or Viscous Groundsel. (Man. p. 

 1029 ; l.'P.f. 4054..) In waste places and on ballast near the coast, N. B. 

 to N. C. — Pennsylvania : Philadelphia, ballast. 



51. ARCTIUM Iv. 



Bracts of the involucre glabrous or nearly so. 1. A. minus. 



Bracts of the involucre copiously woolly. 2. A . lomentosum. 



1. Arctium minus Schk. Common. Burdock. (Man. p. 1030; I. 

 F. f. 40S7. ) In waste places, throughout eastern North America. Nat. 

 from Eu. — Pennsylvania : Common throughout the State. 



2. Arctium tomentoaum (I^am.) Schk. Woolly or Cottony Bur- 

 dock. (Man. p. 1030 ; I. F. y. 40^5.) In waste places, N. B. to Mass. 

 and southern N. Y. Adv. from Eu. — Pennsylvania : Delaware. 



52. CARDUUS L. 



Pappus-bristles, at least those of the inner flowers, plumose. 

 Bracts of the involucre, at least the outer ones, strongly prickle-armed. 

 Leaves glabrous or hispid above, tomentose beneath. 

 Outer and inner bracts of the involucre prickle-armed : naturalized plant . 



I. C. lanceolatus. 

 Outer bracts of the involucre prickle-armed, the inner merely acumi- 

 nate : native plants, 

 lycaf-blades toothed or pinnately lobed. 2. C. allissimus. 



Leaf-blades deeply pinnatifid. . 3. C. discolor. 



Leaves green on both sides, or somewhat pubescent beneath. 



4. C. odoratus. 

 Bracts of the involucre not prickle-tipped or scarcely so. 

 Heads relatively large : involucre about 2 cm. thick or more : flowers per- 

 fect and fruit producing. 

 Heads sessile in an involucre of very spiny bracts. 5. C. spinosissimus. 

 Heads peduncled, not involucrate. 6. C. muHcus. 



Heads relatively small : involucre about i cm. thick : flowers dioecious. 



7. C. arvensis. 

 Pappus-bristles smooth or minutely serrulate. 



Head solitary, nodding ; bracts of the involucre lanceolate. 



8. C. nutans. 

 Head clustered, erect or ascending : bracts of the involucre linear. 



9. C. crispus. 



1. Carduus lanceolatus L. Common Bur or Spear ThisTlE. (Man. 

 p. 1031 ; l.'P.f. 4058.) In fields and waste places, Newf. to Ga., west to 

 Minn., Neb. and Mo. Nat. from Europe. Nat. also frotii Asia. — Penn- 

 sylvania : Lackawanna ; Monroe ; Northampton ; Bucks ; Dela- 

 ware ; Chester ; Lancaster ; Franklin ; Huntingdon ; Alle- 

 gheny. 



