242 COMPOSITAE. 



strap-shaped (ligulate), gamopetalous, epigynous; stamens 5, 

 epipetalous, their anthers united into a tube (syngenesious) ; 

 style 2-cleft at the apex or in sterile flowers usually entire; ovary 

 bicarpellary, inferior, 1-celled, 1-ovuled, with basal placenta; 

 fruit an akene sometimes surmounted by the pappus, often com- 

 pressed at right angles to the subtending chaff (laterally com- 

 pressed) or compressed parallel to the chaff (obcompressed) . 



Corollas strap-shaped in all the flowers of the 

 head; plants with milky juice. 

 Pappus of scale-like or plumose bristles. 

 Flowers not yellow. 



Akenes beaked; flowers violet. 363. Tragopogon, 246. 



Akenes beakless; flowers pink or 



white. 364. Ptiloria, 246. 



Flowers yellow. 



Heads nodding when young; pappus 

 scales 15-20, each with a very 



plumose awn. 365. Ptilocalais, 246. 



Heads erect, even when young; 

 pappus scales less than 15, or if 

 more than 15 awnless. 

 Scales 20-24, not awned. 366. Nothocalais, 247. 



Scales 5-10, with an awn from the 



notched apex. 367. Uropappus, 247. 



Pappus of capillary bristles, never plumose. 

 Heads solitary; leaves all basal. 



Akenes muricate or spinulose at the 



apex. 368. Taraxacum, 247. 



Akenes smooth at the apex. 369. Agoseris, 248. 



Heads several; leaves not all basal. 

 Akenes flattened. 



Akenes beaked, or if short-beaked 



flowers not yellow. 370. Lactuca, 249. 



Akenes beakless; flowers yellow. 371. Sonchus, 249. 

 Akenes terete, cylindric or prismatic. 



Pappus copious, white and soft. 372. Crepis, 250. 

 Pappus a single row of rough 



tawny bristles. 373. Hieracium, 250. 



Corollas tubular in all the flowers of the head or 

 strap-shaped in only the marginal ones; 

 plants without milky juice. 

 Ray flowers none; corollas all tubular. 



Flowers of the heads not all alike, some 



heads having imperfect flowers. 



Perfect and imperfect flowers in the 



same head. 



Marginal flowers neutral and 



st' rile, often larger than the 



central ones, resembling ray 



flowers. 374. Centaurea, 251. 



Marginal flowers perfect or pis- 

 tillate and fertile, not re- 

 sembling ray flowers. 



