XLIII. COMPOSITE. 223 



f Florets all ligul ate (Ligulat^e) 38 



- J Florets all tubular 2 



"J Florets tubular in the disk or centre of each head, the outer ones either ligulate 

 ^ and forming a ray, or slender and filiform (Gorymbifer^:) .... 5 

 ( Involucre or leaves prickly. Style slightly bulbous under the branches (Cyna- 



2-j roide^e) 30 



( Involucre and leaves not prickly 3 



o/ Florets purple, blue, or white 4 



\ Florets yellow or greenish, usually small (Corymbifer<e) 5 



4 J Leaves opposite 1. Eupatorium. 



\ Leaves alternate or radical (Cynaroide^e) .30 



CORYMBIFER^. 



5 / Leaves opposite . . 6 



\ Leaves alternate or radical 7 



( Flower-heads small, numerous, purple. Pappus of many hairs 1. Eupatorium. 

 6-J Flower heads few, rather large, yellow. Pappus of a few 

 ( bristles 11. Bidens. 



i Flower discoid, that is, all the florets of the head tubular or filiform, the outer 

 not longer than the central ones 8 

 Flowers radiate, the outer florets ligulate and spreading, or, if erect, longer than 

 the central ones 19 

 Achenes without a pappus, or crowned by a small cup or short scales . . 9 

 Achenes bearing a pappus of hairs 12 



f Flower-heads monoecious, the males with many tubular florets, the females 

 forming a thick burr, ending in 2 conical beaks, and enclosing 2 flowers. 



10. Xanthium. 

 [Flower-heads all alike 10 



{Receptacle bearing scales between the florets. Plant covered with a dense 

 white cotton. Leaves entire or toothed 16. Diotis. 

 No scales between the florets. Leaves, at least the lower ones, much divided 11 

 f Flower-heads hemispherical, 3 or 4 lines in diameter, in a large terminal corymb. 



,,) Achenes angular, with a flat top 17. Tanacetum. 



J Flower-heads small, often nodding, in a leafy raceme or panicle. Achenes 



V. obovate, contracted at the top 18. Artemisia. 



( Bracts of the involucre linear, equal in length, with a few very small outer 



12 4 ones 13 



( Bracts of the involucre imbricated in 2 or more rows 14 



{Radical leaves large, broadly heart-shaped or orbicular. Stem-leaves small and 

 narrow 19. Tussilago. 

 Leaves pinnate and toothed 20. Senecio. 



{Plants more or less covered with a white cotton or down. Involucral bracts also 

 cottony, or shining and scarious, or coloured at the edge . . . .15 

 Plants not woolly. Involucral bracts narrow and green 17 



I Flower-heads dioecious. Involucral bracts with spreading tips, at least in the 



15 -j males 8. Antennaria. 



( Flower-heads all with tubular florets in the centre. Involucres not spreading 16 



lfi f A row of scales within the outer row of florets 6. Filago. 



\ Receptacle entirely without scales . . . . . .7. Gnaphalium. 



( All the florets tubular and 5-toothed ....... 2. Aster. 



17 < Outer florets of the head linear or filiform, although not longer than the cen- 



( tral ones 18 



} Tall stiff plant. Flower-heads ovoid, in a terminal corymb . 9. Inula Conysa. 



18 •< Flower-heads numerous and small, in a long leafy panicle. 



( 9. Erigeron canadense. 



,q/ Achenes without any pappus, or crowned by a small cup or minute scales . 20 



1 Achenes bearing a pappus of hairs 24 



q J Receptacle bearing scales between the florets, at least among the central ones 21 



1 Receptacle naked (without scales between the florets) 22 



21 / Flower-heads rather large, with a convex or conical receptacle m 14. Anthemis. 



\ Flower-heads small, with a small flat receptacle . . . .15. Achillea, 

 qo /Involucral bracts all green and of equal length 5. Bellis. 



1 Involucral bracts imbricated and scarious at the edges 23 



no J Receptacle flat or convex 12. Chrysanthemum. 



\ Receptacle conical, much elongated as the fruit ripens . .13. Matricaria. 



