262 American Midland Naturalist Monograph No. 7 



2. Leaves palmately cleft or divided, or the uppennost entire. 

 4. Leaves petioled, 3-divided into elliptic-lanceolate segments ; 

 heads many; stem 1-3 m tall; rays entire; pappus none; 

 open woods and along roads. Aiig.-Sept. Tall Tickseed 



C. tripteris L. 



4. Leaves sessile, rigid, 3-cleft at or below the middle, the lobes 

 linear-oblong; heads few or solitary; stem 30-90 cm tall; 

 rays mostly 3-toothed; pappus of 2 short teeth, or none; 



roadsides and open woods. Jime-July C. palmata Nutt. 



1. Leaves or most of them 1- to 2-pinnately parted. 



5. Heads 4-6 cin broad; rays 1.5-2 cm long, yellow throughout; 

 disk yellow; achenes broadly winged; pappus of 2 short 

 scales; plants perennial; roadsides and waste places, occa- 

 sional; adv. from west-central U.S. June-Aug 



C. grandiflora Hogg 



5. Heads 1.5-3 cm broad; rays 8-12 mm long, crimson-brown at 

 base or throughout; disk brownish-purple; achenes linear, 

 wingless; pappus a mere border, or absent; plants annual; 

 roadsides, railroads, or waste places, occasional; adv. from 

 the Great Plains, or sometimes escaped from cult. July-Sept. 

 C. tinctoria Nutt. 



38. Bidens L. — Beggar-ticks. Tickseed. Bur-marigold 

 1. Plants terrestrial; lea\es not finely dissected; achenes flattened. 

 2. Rays inconspicuous or none. 



3. Leaves pinnately parted or dissected. 



4. Achenes linear-fusiform, with 2-4 short-retrorsely barbed 

 awns; rays yellowish-white; roadsides and open woods; 

 chiefly in the southern half of 111., but extending north- 

 ward to Woodford and Henderson counties. Aug.-Sept. 



Spanish Needles B. bipinnata L. 



4. Achenes flat, 2-awned. 



5. Outer bracts 10-16; achenes brown, the awns down- 

 wardly barbed; involucres 10-12 mm high; roadsides, 



fields, and woods, local. Aug.-Oct 



B. vulgata Greene 



5. Outer bracts 4-8; achenes black. 



6. Awns of the achenes upwardly barbed ; wet ground, 



not common. Aug.-Oct 



_...'. B. discoidca (T. & G.) Britt. 



6. Awns downwardly barbed; roadsides, fields, wet 



ground, and open woods. Aug.-Oct 



B. jrondosa L. 



3. Leaves simple, lanceolate, toothed or lobed, sessile or peti- 

 oled; awns of the pappus 3 or 4. 

 7. Outer bracts rarely much exceeding the disk; achenes 

 4- angled, 4-6 mm long; corollas 5-toothed; stamens ex- 

 serted; wet ground throughout 111. Sept. -Oct. Swamp 

 Beggar-ticks B. connata Muhl. 



