158 SELECTED WESTEKN FLORA 



1. L. pulchella, (Pursh.) DC. Blue Lettuce. 



Stem simple, glaucous, 1-2 ft. high; leaves sessile, entire, or the lower 

 slightly pinnatifid ; flowers blue. Common. 



2. L. spicata, (Lam.) Hitchc. 



Biennial, smooth, tall, 3-7 ft. high, stout, leafy ; leaves irregularly pinnati- 

 fid or coarsely toothed; heads numerous in a dense compound panicle; 

 flowers purplish; pappus brown. Damp thickets, Man.-Alta. 



41. LYGODESMIA. 



Heads 3-12-flowered, solitary at the ends of the branches. 

 Smooth rush-like herbs with leaves linear or often reduced to scales, 

 and pinkish-purple flowers. 



1. L. juncea, Don. 



Perennial from a stout root; stem rigid, much branched; leaves linear, 

 rigid, gradually reduced upwards to scales; heads mostly 5-flowered. Dry 

 sandy prairies, Man.-Alta. 



42. PRENANTHES. Rattlesnake Root. 



Heads small, 5-30-flowered, flowers all ligulate; involucre of 1 

 row of 5-14 main bracts and a few smaller outer ones; pappus of 

 numerous white to brown coarse bristles. Upright, leafy, perennial 

 herbs from a tuberous rootstock with more or less nodding heads of 

 rather dull-colored flowers. 



1. P. racemdsa, Michx. 



Stem 2-6 ft. high; leaves oval to lanceolate, sometimes pinnatifid, the 

 lower petioled, the upper clasping; glaucous throughout; heads 12-15- 

 flowered, almost erect; flowers purplish; pappus straw-colored. Moist 

 prairies and thickets, Man.-Alta. 



2. P. alba, L. 



Smooth, stout, 2-5 ft. high, purplish; leaves hastate, ovate, or cordate, 

 and variously toothed or lobed, or the upper lanceolate and entire, the lower 

 petioled, the upper sessile; heads nodding, 8-12-flowered; involucre, of 

 6-8 principal bracts, whitish green or purple; flowers whitish; pappus 

 reddish-brown. Borders of woods and thickets, Man.-Alta. 



3. P. altissima, L. 



Slender, smooth, 3-6 ft. high ; heads in small clusters forming a long coni- 

 cal panicle; leaves petioled, ovate to heart-shaped, toothed or lobed, or 

 3-6-parted, the divisions sometimes still further divided; flowers greenish 

 white. Man. and westward. 



