CICHORIACEAE 1311 



columnar, terete or 5-angled, often 10-ribbed, truncate. Pappus of numerous hair-like 

 rather rigid pale or brown bristles. RATTLESNAKE-BOOT. WHITE LETTUCE. 



Bracts of the involucres glabrous or sometimes with a few scattered hairs. 



Involucres slender, about 2 mm. thick, 5-7-flowered, light green : pappus light straw-colored, 



1. N. altissimm. 

 Involucres stout, 3-6 mm. thick, 8-16-flowered. deep green, glaucous or purple. 



Pappus deep cinnamon-colored. 2. N. albus. 



Pappus straw-color or light brown. 



Leaf-blades merely toothed or somewhat incised. 



Larger bracts of the outer involucre lanceolate : lower leaf-blades ob- 

 long to oval, not cordate. 3. N. integrtfolius. 

 Larger bracts of the outer involucre ovate : lower leaf-blades hastate, 



cordate. 4. N. Roanensis. 



Leaf-blades, at least some of them pinnatifid, lobed or divided. 

 Inflorescence paniculate. 



Panicles much broadened upward : bracts of the involucres, at least 



the longer ones, glabrous. 



Larger bracts of the outer involucre lanceolate : pappus surpass- 

 ing the inner involucral bracts. 5. N. serpentarius. 

 Larger bracts of the outer involucre ovate, or triangular-ovate : 



pappus and inner involucral bracts about equal in length. 6. N. trifoliatus. 

 Panicles cylindric : bracts of the involucres sparingly hairy. 7. N. cylindricus. 



Inflorescence raceme-like. 8. N. virgatus. 



Bracts of the involucres copiously pubescent. 



Involucres 8-16-flowered : inflorescence thyrsoid. 9. N. asper. 



Involucres 20-25-flowered : inflorescence corymbose-paniculate. 10. N. crepidineus. 



1. Nabalus altissimus (L.) Hook. Perennial, glabrous or nearly so, not glaucous. 

 Stems erect, 1-2 m. tall, narrowly branched above : leaf-blades thin, usually light green, 

 5-15 cm. long, the lower usually hastately 3-5-lobed on long slender petioles, the upper has- 

 tate, deltoid, ovate or oblong-lanceolate, more or less strongly dentate, rounded or cordate 

 at the base or those of the inflorescence attenuate below : involucres 5-7-flowered, slender, 

 10-12 mm. long, about 2 mm. thick ; inner bracts narrowly linear, glabrous : ligules 

 greenish or yellowish : achenes slender, 4-5 mm. long : pappus light straw-colored. 

 [Prenanthes altissimus L.] 



In woods and on hillsides, Newfoundland to Manitoba, Georgia and Tennessee. Summer and fall. 



2. Nabalus albus (L. ) Hook. Perennial, glabrous or nearly so, often glaucescent. 

 Stems erect, 3-16 dm. tall, narrowly branched above, finely ridged in age : leaf-blades del- 

 toid, triangular or sometimes broader than long, more or less deeply hastate ; segments 

 lobed or dentate : involucres 10-12 mm. long ; outer bracts triangular to lanceolate, the 

 inner linear, glabrous or puberulent : ligules dull white or cream-colored : achenes about 

 5 mm. long : pappus cinnamon or cinnamon-brown. \_Prenanihes alba L.] 



On banks or in woods, Maine to Ontario, Manitoba, Georgia and Kentucky. Summer and fall. 



3. Nabalus integrlfolius Cass. Perennial, hirsute or glabrate. Stems 4-18 dm. 

 tall, more or less branched above, the branches often sharply ridged : leaf-blades oblong, 

 varying to oval-oblong or oblong-lanceolate, sometimes slightly sagittate at the base, sinu- 

 ate or sinuate-dentate, more or less abruptly narrowed into winged petioles or the upper 

 sessile : involucres 11-15 mm. long ; inner bracts linear, bristly-hirsute or glabrate : 

 achenes 4.5-5 mm. long : pappus dirty brown. 



On mountain slopes or in woods, New York to North Carolina and Georgia. Late summer and fall. 



4. Nabalus Roane'nsis Chickering. Perennial, more or less hirsute. Stems erect, 

 3-5 dm. tall, topped by a narrowly cylindric panicle : leaf-blades triangular-hastate to 

 hastate-lanceolate, 3-10 cm. long, acuminate, dentate or incised and dentate, pale beneath, 

 truncate to cordate at the base ; petioles as long as the blades, or shorter : involucres 8-10 

 mm. long; inner bracts linear, more or less hirsute: achenes 4-4.5 mm. long: pappus 

 dingy straw-colored. 



On the summit of Roan Mountain, North Carolina, and on neighboring peaks. Summer and fall. 



5. Nabalus serpentarius (Pursh) Hook. Perennial, glabrous or nearly so. Stems 

 3-10 dm. tall, branching above, the branches often widely spreading : leaf-blades 5-30 

 cm. long, pinnately or hastately 3-7-lobed, narrowed into winged petioles or the upper ses- 

 sile ; lobes toothed or incised : involucres 10-12 mm. long ; outer bracts mostly lanceolate, 

 occasionally pubescent ; inner bracts linear, glabrous: achenes 4.5-5 mm. long : pappus 

 straw-colored. [Prenanthes serpentaria Pursh.] 



In open woods, fields or thickets, Ontario to Florida, Kentucky and Alabama. Summer and fall. 



6. Nabalus trifoliatus Cass. Perennial, deep green, glabrous. Stems erect, 8-26 

 dm. tall, more or less widely branching above : leaves various ; blades thinnish, those of 

 basal and lower stem-leaves 1-3 dm. long, usually 3-divided, long-petioled ; segments lobed 

 or toothed, sessile or stalked : blades of the upper leaves gradually less lobed, and on the 

 upper part of the stem they are sometimes lanceolate and entire : heads 7-12-flowered, 



