COMPOSITE. 413 



acheue of each partly embraced by, or closely enfolded within its invo- 

 lucral bract. Chaff of receptacle often in a single row between ray and 

 disk, and united into a cup. Disk-corollas usually hairy. Style- 

 branches subulate, hispid. 



Hints of the Cieiiera. 



* Ray-achenes distinctly incurved. 



Kay-corf)llas ample and showy, yellow -----.----56 

 Kay-corollas minute, usually very few --------- 57 



* * Ray-achenes commonly gibbous, hut not incurved. 



Ray-achenes smooth, laterally compressed, nearly or quite enclosed by their bracts; 



Receptacle glabrous ---.----.--55 



Receptacle fimbrillate-hirsute ---..--. 53 



Ray-achenes smooth, somewhat obcompressed, half enclosed by their bracts; 



Pappus none in either disk or ray ------,-59 



Pappus present, at least in the disk; 



Pappus plumose .1-------60, 70 



" paleaceous -------- -gi 



Ray-achenes tuberculate or rugose, half enclosed by their bracts; 

 Receptacle bracted only between ray and disk; 



Bracts of involucre 5 to 8, with short erect rigid tips - - - - 61, 62 



Bracts of involucre 15 or more, with longer spreading soft tips - - 63 

 Receptacle chaffy throughout, i. e., a bract to each flower; 



Involucral bracts gland-tipped - - - - - - - - 62, 64 



" " spinescent-tipped -------.65 



* * * Ray-achenes obcompressed, or else clavate and not compressed, nearly 

 or quite enfolded by their bracts. 



Rays 8 to 15, showy; pappus of bristles or sharp-pointed paleae, the latter often very 

 villous below ---------.--.- gg 



Rays short, inconspicuous; pajjpus of blunt silvery-white scales - - - - 67 



Rays 5 to 8, large in proportion to the small heads; 



Pappus none; rays yellow ---.---.. gg 



Pappus of ray cupnliform; rays white - ------gg 



Pappus of disk and ray plumose -------- 79 



55. MADIA, Molina. (Tarweed.) Glandular and viscid heavy- 

 scented herbs, with at least the upper leaves alternate, entire, or merely 

 toothed. Heads axillary and terminal, the yellow flowers vespertine, 

 closing in sunshine. Involucre angled by the salient carinate backs of 

 the uniserial involucral bracts; these usually completely enfolding the 

 laterally compressed smooth achene, and having free herbaceous tips. 

 Receptacle fiat or convex, bearing a single series of chaff united and 

 forming a cup which separates between rays and disk-flowers, otherwise 

 naked. Ligules 3-lobed. Bracts of involucre deciduous with the mature 

 achenes (except in n. 2); these smooth, beakless. 



