125. CoMPOsiTAE 237 



59. Leaves incised or coarsely and irregularly toothed 



46. Chrysanthemum 



57. Leaves entire to serrate or dentate. 



60. Rays purple, reflexed; receptacle conical or columnar. 

 60. Rays white or pink, not reflexed. 



61. Rays many, lilac or white; leaves entire, lanceolate 

 18. Boltonia 



61. Rays 3-5, white, short. 



62. Heads campanulate; pappus of 2 slender 



awns; leaves entire to serrate 



35. Verbesina 



62. Heads hemispheric; pappus of 2 or 3 incon- 

 spicuous scales; leaves dentate 



27. Parthenium 



34. Heads rayless. 



63. Flowers green or greenish. 



64. Staminate and pistillate flowers in the same head, or flowers all 

 perfect. 



65. Heads few or solitary; receptacle conical; bracts short, oval, 

 obtuse, scarious; leaves finely dissected, with pineapple 

 odor when crushed 45. Matricaria 



65. Heads numerous, in spikes, racemes, or panicles. 



66. Heads in long terminal bracted spikes; receptacle bristly 

 or chafTy; leaves opposite, or the upper alternate, 



entire or serrate I. Iva 



66. Heads in panicles or racemes; receptacle smooth; leaves 

 alternate, mostly lobed or incised; plants bitter-aromatic 



48. Artemisia 



64. Staminate and pistillate flowers in separate dissimilar heads. 



67. Involucre of pistillate heads with hooked prickles 



4. Xanthium 



67. Involucre of pistillate heads merely tuberculate, or with 

 straight spines. 

 68. Pistillate involucre with a single series of spines or 



tubercles 2. Ambrosia 



68. Pistillate in\olucre with sc\eral series of spines or 



tubercles 3. Franseria 



63. Flowers yellow (or yellowish) or white. 

 69. Flowers white. 



70. Leaves alternate, pinnatifid 39. Hymenopappus 



70. Leaves opposite, entire to lobed 36. Melanthera 



69. Flowers yellow or yellowish ; bracts green. 



71. Leaves alternate or basal. 



72. Leaves pinnately dissected 47. Tanacetum 



72. Leaves shallowly lobed, prickly-margined 58. Cnicus 



7 1 . Leaves opposite. 



73. Pappus none; achenes thick, not flattened; disk-flowers 



perfect but sterile; plants glandular-pubescent, odorous 



25. Polymnia 



73. Pappus of 2-4 awns or teeth; achenes flattened; disk- 

 flowers fertile; plants not glandular 38. Bidens 



