334 COMPOSITE 



43 Helianthus Achenes thick, quadrangular-compressed or with the 

 sides convex and the angles obtuse : pappus a pair of caducous chaffy 

 scales or awns. 



Subtribe iv, Bidentiae^e Heads radiate, the rays neutral or 

 pistillate. Receptacle chaffy with flat or barely concave decidu- 

 ous chaff. Achenes all obcompressed Pappus of 2-4 teeth or 

 awns from the angles, or none. 



44 Coreopsis Achenes never rostrate-attenuate nor with retrorsely barb- 



ed awns. 



45 Bidens Achenes neither winged nor beaked, 2-5-awned with retrorse- 



ly barbed persistent awns. 



Subtribe v, Galinsogej^ Heads heterogamous with the ray- 

 flowers, when pr- sent, fertile; disk-flowers either perfect and 

 fertile or sterile, Achenes neither compressed nor obeompressed. 

 Pappus in both ray- and disk-flowers few to numerous chaffy 

 scales. 



46 Blepharipappus Heads radiate ; the rays pistillate : pappus of 12-20 



thin scales with a stout midrib. 



Subtribe vi, Mad-ie^e Heads heterogamous; ray-flowers, when 

 present, fertile ; disk-flowers either perfect and fertile, or sterile. 

 Involucre a series of bracts, each subtending and more or less en- 

 closing a ray-achene. Receptacle chaffy only at the margin, the 

 chaff forming a sort of inner involucre or else subtending some or 

 all of the disk flowers 



* Achenes all laterally compressed ; those ef the ray wholly enclosed 

 in the carinate strongly infolded bracts of the involucre. 



47 Anisocarpus Rays conspicuous and mostly numerous, fertile; disk- 



flowers numerous, sterile or tne exterior ones fertile; with pubescent 

 corolla and a pappus composed of fimbriate or plumose-lacerate scales. 



48 Madaria Rays numerous and conspicuons : disk-flowers without pap- 



pus, either ail or only the central ones sterile. 



49 Madia Rays 1-12 or none, short and more or less inconspicuous : disk- 



flowers numerous or few, all fertile, destitute of pappus. 



50 Harpaecarpus Rays 4-8, very short and inconspicuous; disk-flower 

 solitary, fertile, enclosed in a 3-5-toothed herbaeeous cup : pappus none. 



* * Achenes of the ray-flowers turgid, more or less oblique or incurv- 

 ed, never laterally compressed but mostly so fie what obcompressed: 

 bracts of the involucre each investing an achene, rounded on the back. 



51 Hemizonella Involucre stronglg 4-5-sulcate by the complete enwrap- 

 ing of the 4 or 5 achenes : disk-flower solitary in a sore of inner invo- 

 lucre : pappus none. 



52 Hemizonia Achenes of the ray-flowers obovate-triangular, with de- 

 pressed terminal areola; disk -flowers numerous, with abortive achenes : 

 pappus none. 



53 Calycadenia Achenes of the ray-flowers obovoid, the terminal areola 

 little if at all oblique, tiiangular; of the numerous disk-flowers well 

 formed, and sometimes truly fertile, surrounded by a cirele of herba- 

 ceou bracts ; paj pus of conspicuous chaffy scales. • 



