918 FLORA. 



Filaments united below. 99. Mariana. 



Receptacle fleshy, not bristly. 100. Onopordon. 



* * Achenes obliquely inserted on the receptacle. 

 Heads not subtended by bristly leaves; involucral bracts often bristly. 



101. Centaurea. 

 Heads sessile, subtended by bristly leaves. 102. Cm'cus. 



i. VERNONIA Schreb. 



Erect branching perennial herbs, or some tropical species shrubby, with alter- 

 nate (very rarely opposite), in our species sessile leaves, and discoid cymose-panic- 

 ulate heads of purple, pink, or white tubular flowers. Involucre hemispheric, 

 campanulate or oblong-cylindric, its bracts imbricated in several or many series. 

 Receptacle flat, naked. Corolla regular, 5-cleft. Anthers sagittate at the base, 

 not caudate. Style-branches subulate, hispidulous their whole length. Achenes 

 8-io-ribbed, truncate. Pappus of our species in 2 series, the inner of numerous 

 roughened capillary bristles, the outer of much shorter small scales or stout bris- 

 tles. [Named after William Vernon, English botanist.] About 475 species, of 

 wide distribution in warm-temperate regions, most abundant in S. Am. Besides 

 the following, 2 or 3 others occur in the southern and southwestern U. S. 



Bracts of the hemispheric involucre, or some of them, with subulate or filiform tips. 



Involucre 6-10 mm. broad, its bracts shorter than the head. i. V. Noveboracensis. 

 Involucre 18-25 mm. broad, its bracts as long as the head. 2. V. crinita. 

 Bracts of the involucre merely acute, obtuse or truncate. 

 Leaves lanceolate to oval, pinnately veined. 



Bracts of the involucre with squarrose tips. 3. V. Baldwinii. 



Bracts of the involucre appressed or their tips slightly spreading. 

 Leaves glabrous or very nearly so on both surfaces. 



Leaves thin, pale beneath, the lower oval, coarsely serrate. 



4. V. glauca. 

 Leaves thin, green beneath, lanceolate, finely serrate. 



5. V. gigantea. 

 Leaves thick, narrowly lanceolate, sharply serrate. 6. V.fasciculata. 



Leaves densely pubescent beneath, lanceolate. 



Involucre 8-12 mm. high ; plant tomentose. 7. V. Drummondii. 



Involucre 6-7 mm. high; plant pubescent. 8. V. interior. 



Leaves narrowly linear, i-nerved, 4-6 mm. wide, dentate. 9. V. marginata. 



1. Vernonia Noveboracensis (L.) Willd. NEW YORK IRON-WEED. FLAT 

 TOP. (I. F. f. 3601.) Roughish-pubescent or glabrate, 9-27 dm. high. Leaves 

 lanceolate or narrowly oblong, serrulate, 7-25 cm. long, 10-25 mm. wide, acumi- 

 nate or acute at the apex; heads peduncled; involucre 20-30- flowered; bracts 

 brownish-purple, ovate or ovate-lanceolate, tipped with subulate spreading awns 

 usually of twice or three times their own length, or some of the lower linear subu- 

 late, the upper sometimes merely acute; flowers deep purple, rarely white; achenes 

 hispidulous on the ribs. In moist soil, Mass, to Minn., Ga. and Kans. July-Sept. 



Vernonia Noveboracensis toment6sa (Walt.) Britton. Leaves densely puberulent 

 beneath, broader; involucre purple, some scales sometimes merely acute. In dry soil, 

 Va. to N. Car. 



2. Vernonia crinita Raf. GREAT IRON-WEED. (I. F. f. 3602.) Stout, 

 glabrate or finely rough-pubescent, 25-35 dm. high. Leaves narrowly lanceolate, 

 finely denticulate, acuminate. 10-30 cm. long, 6-25 mm. wide; heads stout- 

 peduncled, the peduncles thickened above; involucre 50-70 flowered; bracts green, 

 or the upper reddish, very squarrose, all filiform-subulate from a broader base and 

 equalling the head, the inner ones somewhat wider below; achenes hispidulous on 

 the ribs. On prairies and along streams, Mo. and Kans. to Tex. Aug.-Oct. 



3. Vernonia Baldwinii Torn BALDWIN'S IRON-WEED. (I. F. f. 3603.) 

 Stout, 6-16 dm. high, finely and densely tomentose-pubescent. Leaves lanceolate 

 or oblong-lanceolate, acuminate or acute at the apex, sharply serrate, 10-20 cm. 

 long, 1-2.5 cm. wide, scabrate above, densely tomentulose beneath; heads stout- 

 peduncled, 15 -30 -flowered; involucre hemispheric, 6-8 mm broad; bracts ovate, 

 the acute tips recurved or spreading. In dry soil, Mo. and Neb. to Tex. July- 

 Sept. 



