314 CICHORIACEAE. 



Pappus of scales, or of both scales and pliimeless bristles, or 

 wanting. 

 Ligules yellow or orange. 



Annual plants : achene of a turbinate type : pappus- 

 scales large, accompanied by as many bristles. 11. Krigia. 

 Perennial plants : achene of an oblong type : pappus- 

 scales minute, accompanied by more numerous 



bristles. 12. Cynthia. 



Ligules white, pink, blue, or purple. 13. Cichoeidm. 



1. NABALUS Cass. Perennial caulescent herbs. Leaf-blades toothed, 

 lobed, pinnatifid, or divided. Heads nodding. Involucre cylindric or nearly 

 so : main bracts nearly equal in length, Achenes oblong to columnar. — Sum. 

 and fall. — ■ Eattlesxake-koot. White-lettuce. 



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

 colored. 1. N. altissimus. 

 Involucres stout, 3-6 mm. thick, 8-16-flowered, deep-green, glau- 

 cous, or purple. 

 Pappus cinnamon-brown : corollas mostly whitish. 2. N. alius. 

 Pappus straw-colored or light-brown : corollas mostly purplish. 

 Larger bracts of the outer involucre lanceolate : pappus 



surpassing the inner involucral bracts. 3. N. serpentarius. 



Larger bracts of the outer involucre ovate or triangular- 

 ovate : pappus and inner involucral bracts about equal 

 in length. 4. JV. trifoliatvs. 



1. N. altissimus (L.) Hook. Stems 9-21 dm. tall, glabrous, glaucous: leaf- 

 blades denticulate, or lobed or divided and with denticulate or lobed divi- 

 sions: involucres less than 3 m. thick, the outer bracts of the involucre deltoid 

 to ovate, 1-2 mm. long, the inner ones 9-10 mm. long, light-green, glabrous: 

 ligules greenish or yellowish. — N. S. Not very common, in low thickets. — 

 Sandstones and shales, schists. 



2. N. albus (L.) Hook. Stems 3-16 dm. tall, glabrous, glaucous: leaf -blades, 

 or the divisions, coarsely toothed: outer bracts of the involucre ovate, 2-3 mm. 

 long, the inner ones 10-12 mm. long, dark-green, glabrous: ligules dull-white 

 or cream-colored. — Common, in woods and thickets. 



3. N. serpentarius (Pursh) Hook. Stems 3-12 dm. tall, glabrous: larger leaf- 

 blades pinnately lobed: inner bracts of the involucre 9-11 mm. long, often 

 ciliate at the tip : pappus straw-colored. — S. Eather common, in thickets. — 

 Schists. — Lion 's-foot. 



4. N. trifoliatus Cass. Stems 8-26 dm. tall, glabrous: larger leaf -blades 

 pedately lobed: inner bracts of the involucre 9-11 mm. long, wholly glabrous: 

 pappus light-brown. — S. Common, in woods. — Schists. — Gall-of-the-earth. 



2. CBrEFIS L. Annual or biennial herbs, resembling Eieracium, with 

 glabrous or sparingly pubescent foliage. Leaves alternate: blades mostly 

 repand or pinnatifid. Heads few-many-flowered, paniculate or corymbose. 

 Involucres narrow: bracts usually in a single row or in several rows. Corollas 

 yellow. Achenes narrow. Pappus of white soft hairs. 



1. C. tectorum L. Plants usually branched at the base, 2-4 dm. tail, sparingly 

 pubescent: leaf-blades oblong, lanceolate, or linear-lanceolate in outline, runci- 

 nate-pinnatifid, usually sagittate-auriculate at the base: involucres 9-10 mm. 

 high; bracts hirsute-hispid, acute: corollas 10-11 mm. long: achene-body 

 oblong or somewhat fusiform, about 2 mm. long, ribbed. — S. Occasional, in 

 alfalfa fields. Nat. of Eu. — Fall. — Hawksbeard. 



3. HIEEACIUM L. Perennial caulescent or scapose herbs. Leaf -blades 

 entire or toothed. Heads erect. Involucres usually narrow: main bracts 

 unequal in length. Achenes oblong, fusiform, or columnar. — Hawkv5^eed. 



