40f> COMPOSITAE. 



A, Radical leaves broad, palmately cleft or parted. 

 ( '.inline leaves scale-like; flowers subdioecious, whitish; pistillate corollas distinctly 



ligulate 23. Petasites. 



C. inline leaves similar to the radical; flowers all perfect and fertile, yellow; rays none.... 



24. Cacaliopsis. 

 /?. heaves not palmately parted; flowers yellow. 

 Bracts of the involucre linear, rigid; heads rayless; leaves entire, sessile, white-woolly 



beneath 25. Luina. 



Bracts of the involucre thin-herbaceous; heads radiate or rayless; leaves various. 



Leaves chiefly opposite; heads large 26. Arnica. 



Leaves alternate; heads large or small 27. Senecio. 



Tribe 4. Anthemideae. Mayweed Tribe. 



Strong-scouted or aromatic plants. Leaves alternate, all or some of them 

 finely dissected, pinnately parted or pinnatifid, except one species. Bracts of 

 the involucre imbricated, commonly dry and scarious or with scarious margins. 

 Eeceptacle naked or with chaff -like bracts. Flowers white, yellow or greenish. 

 Eays present or none. Anthers not caudate. Pappus none or a short scarious 

 crown. 



A. Receptacle with chaff-like bracts. 



Heads solitary, terminating leafy branches or peduncles; rays 14 to 20; annual 



28. Anthemis. 



Heads in a terminal corymb; rays 4 or 5; perennial 29. Achillea. 



B. Receptacle naked. 

 All of the flowers with a corolla. 



Heads solitary, terminating leafy branches or peduncles. 



Rays many, conspicuous 30. Chrysanthemum. 



Rays none; flowers all alike, perfect, greenish; annual 31. Matricaria. 



Heads corymbose; rays none; flowers yellow; perennial 32. Tanacetum. 



Heads in panicled racemes or spikes, small; rays none; flowers yellow or purplish; 



shrubs or herbs 33. Artemisia. 



Marginal flowers without a corolla; heads discoid. 



Heads peduncled; mature achenes borne on pedicels; style deciduous 34. Cotula. 



Heads sessile; achenes pointed with the spine-like persistent style 35. Soliva. 



Tribe 5. Helenieae. Sneezeweed Tribe. 



Herbs or some Eriophyllums suffruticose. Leaves alternate or opposite. 

 Flowers in our species yellow. Eays present in all our species except Chaenac- 

 tis. Anthers not caudate. Eeceptacle naked. Bracts of the involucre in 1 or 

 2, sometimes in 3 or 4 (?) series. Pappus of paleae, awns or bristles, or often 

 wanting. 



A. Leaves opposite; herbage glabrous, pubescent or slightly tomentose, never white-woolly. 

 Bracts of the involucre imbricated, in more than 1 series; pappus none; succulent per- 

 ennial 36. Jaumea. 



Bracts of the involucre in a single series and 



United into a toothed cup; pappus paleaceous or none; annuals 37. Lasthenia. 



Distinct; pappus of paleae or bristles, or both, or none; annuals except one.. 38. Baeria. 

 B. Leaves alternate; herbage glabrous or in several genera white-woolly. 

 Ray-corollas with a toothed appendage at base opposite the ligule; pappus none; leaves 



entire or denticulate ; annuals 39. Monolopia. 



Ray-corollas without appendage at base. 

 Pappus present. 



Bracts of the involucre erect. 



Rays conspicuous; paleae firm, blunt; leaves divided or incised; perennial herbs 



or suffruticose plants 40. Eriophyllum. 



Rays very inconspicuous; paleae subulate; leaves narrowly linear and entire; slen- 

 der annuals 41. Rigiopappus. 



Rays none or the marginal corollas palmately enlarged; leaves divided; annuals.... 



42. Chaenactis. 



Bracts of the involucre reflexed; rays usually drooping; paleae short-pointed; leaves 



often decunent; perennial herbs 43. HeLENIUM. 



Pappus none; leaves pinnately parted; low annual 44. Blennosperma. 



