CICHOEIACEAE. 315 



Stems regularly leafy to the broad, more or less effuse panicle : leaf-blades not of 

 a spatulate type. 1. H. paniculutum. 



Stems more or less scape-like, corymbose or narrowly cylindric- 

 paniculate above : leaves mainly basal, or on the lower 

 part of the stem, some of the lower blades of a spatulate 

 type. 

 Achenes columnar. 



Longer involucral bracts glabrous or nearly so. 



Stems nearly naked, glabrous : peduncles glabrous or 



sparingly glandular-pubescent. 2. B. venosum. 



Stems leafy and pubescent at least below : peduncles 



densely glandular-pubescent. 3. H. marianum. 



Longer involucral bracts copiously pubescent. 4. H. scabrum. 



Achenes fusiform or constricted below the summit. 5. H. OronovU. 



1. H. paniculatum L. Plants often glaucescent, 3-12 dm. tall, the stem villous 

 at the base: leaf -blades linear-elliptic to broadly elliptic: involucres 4-5.5 mm. 

 high, the longer bracts pubescent mainly near the tip. — Common, in woods 

 and thickets. — Late sum. 



2. H. venosum L. Stems scape-like, 3-6 dm. tall, glabrous, corymbosely 

 branched above : leaves mainly basal, or 1 or 2 on the stem ; blades obovate or 

 spatulate, 5-15 cm. long, commonly purple-veined, undulate or repand-denticu- 

 late, more or less villous on the veins beneath: peduncles slender, often slightly 

 glandular-pubescent: involucres 6-8 mm. long; inner bracts linear, tapering to 

 the apex : achenes columnar, about 3 mm. long. — Common on banks and in 

 open woods. — Sum. — Eattlesnake-weed. Poor-Eobin 's plantain. 



3. H. marianum Willd. Stems rather stout, 5-10 dm. tall, softly hirsute below, 

 more or less widely branched into a corymbose panicle: leaves basal, and few 

 or several along the stem ; blades spatulate to oblong-obovate or nearly oblong, 

 6-20 cm. long, ciliate, undulate or repand-denticulate: peduncles densely glan- 

 dular-pubescent: involucres 6-7 mm. long; inner bracts narrowly linear-lanceo- 

 late, glabrous or slightly pubescent : achenes columnar, 2.5 mm. long. — M. 

 Occasional, on banks and in open woods. — Limestones. — Spr. 



4. H. scabrum Michx. Stems 3-9 dm. tall, hirsute-hispid below, paniculately 

 branched and glandular-hirsute above, leafy to the inflorescence: leaf -blades 

 thickish, spatulate to obovate or oblong, 3-12 em. long, undulate or repand- 

 denticulate: panicle commonly elongate: peduncles rather rigid: involucres 

 5-6 mm. long; inner bracts narrowly linear-lanceolate: achenes columnar, 2-2.5 

 mm. long. — Common, in woods and on roadsides. — Fall. 



5. H. Gronovii L. Stems 3-10 dm. tall, more or less pubescent with slender 

 hairs, paniculately branched above, leafy below, rather naked near the panicle: 

 leaves commonly hirsute; blades spatulate to oblong, oval or obovate, 4-15 cm. 

 long, undulate or repand: panicle ample or sometimes much reduced: peduncles 

 glandular-pubescent: involucres 5-7 em. long; inner bracts linear or narrowly 

 linear-lanceolate : achenes fusiform, 3-3.5 mm. long. — Common, on gravelly 

 banks and in woods. — Simi. and fall. 



4. IiACTUCA L. Annual, biennial, or perennial herbs, the stems stout. 

 Leaf-blades mostly relatively broad, entire, toothed, or pinnatifid, sometimes 

 spiny-margined. Heads erect. Involucres cylindric to ovoid. Achenes flat- 

 tened, slender-beaked. — Sum. and fall. — Lettuce. Wood-lettuce. Wild- 

 lettuce. 



Heads mostly less than 12-flowered : achene-bodies several-nerved. 



Leaf-blades pinnatifid. 1- L. Scariola. 



Leaf-blades merely toothed. 2. L. virosa. 



Heads mostly more than 12-flowered: achene-bodies 1-nerved. 

 Leaf-blades entire or nearly so: achene-body mostly less 



than 3 mm. long. 3. L. sagittifoHa. 



Leaf -blades, except those of the upper leaves, pmnatifld : 



achene-body mostly over 3 mm. long. 4. L. canadensis. 



