3(2). Principal cauline leaves usually 10-30 mm. broad 2. V. fasciculate. 



3. Principal cauline leaves usually 1-6 (-8) mm. broad (4) 



4(3). Leaves usually 2-6 mm. broad, scabrous; achenes 4-5 mm. long 



3. V. marglnata. 



4. Leaves usually 1-1.5 mm. broad, smooth; achenes 3-4 mm. long 



4. V. Lettermannii. 



5(2). Lower surface of the leaves tomentose, at least along the veins; flowers 34 

 to 55 per head 5. V. missurica. 



5. Lower surface of the leaves with straight or slightly curly hairs; flowers 13 to 



29 per head 6. V. altissima. 



1. Vernonia crinita Raf. Fig. 742. 



Stems 1-3 m. tall, leafy, commonly glabrous and somewhat glaucous, occasion- 

 ally minutely puberulent; leaves linear or linear-lanceolate, 10-18 cm. long, 5-20 

 mm. broad, acuminate, commonly denticulate or sometimes nearly entire, typically 

 glabrous, rarely thinly pubescent, impressed-punctate beneath; inflorescence very 

 irregular, the peduncles 1-5 cm. long, thickened at the summit; heads 55- to 

 90-flowered; involucre 10-12 mm. high; phyllaries glabrous or pubescent, linear 

 or narrowly lanceolate at the appressed base, tapering to a loosely flexuous filiform 

 tip; achenes strongly ribbed, glabrous or nearly so, 5-6 mm. long; pappus dull 

 purple. 



On gravel and sand bars along streams, borders of sloughs, wet meadows, 

 prairies and moist open woods, in Okla. (Mayes, Craig, Ottawa and Cherokee 

 COS.), July-Oct.; cen. Mo. to e. Kan., Ark. and Okla. 



2. Vernonia fasciculata Michx. 



Stems to 2 m. tall, glabrous, often red or purple; leaves linear to linear- 

 lanceolate, denticulate to sharply serrate, glabrous on both sides, conspicuously 

 pitted beneath, the larger 1-2 (-3) cm. broad; inflorescence usually flat and 

 densely flowered, 4-20 cm. wide; heads 20- to 30-flowered; involucre 6-9 mm. 

 high, to 2 mm. wide; principal phyllaries rounded lo subacute, entirely or sparsely 

 ciliate, commonly glabrous on the back; achenes glabrous or puberulent on the 

 ribs, resinous in the furrows, about 3 mm. long; pappus purple. 



In wet prairies and marshes, wet river bottom meadows, along streams, and 

 in upland fields and rich moist soil, n. Okla. (Osage Co.), reported from Tex., 

 July-Sept.; O. to Minn, and Sask., s. to Mo., Okla. and (?) Tex. 



3. Vernonia marginata (Torr.) Raf. Plains ironweed. 



Stems erect, simple or rarely branched below the head-bearing region, 4-10 

 dm. tall, glabrous or minutely puberulent; leaf blades firm-membranous, linear 

 to linear-lanceolate, 5-10 cm. long, 2-6 (-8) mm. broad, acute or acuminate, 

 entire or remotely denticulate, essentially glabrous, pitted underneath; involucre 

 broadly campanulate to thick-cylindric, about 8 mm. broad, 7-10 mm. high; 

 phyllaries appressed, closely and regularly imbricate, mostly acute, glabrous or 

 nearly so except in some specimens on the margins; flowers about 18 to 21 per 

 head; achenes 4-5 mm. long, glabrous, with resin-globules in the furrows. V. 

 tenui folia Small. 



In low open meadows near ponds, along streams, about pools in washes, dunes 

 and shallow swales, s.w. Okla. (Waterfall), the Trans-Pecos and Plains Country 

 of Tex., and e. N.M. (Guadalupe, Chaves and Quay cos.), summer; Kan., Okla., 

 Tex. and N. M. 



4. Vernonia Lettermannii Engelm. 



Stem erect, simple except in the uppermost parts, 5-7 dm. tall; cauline leaves 



1593 



