SUNFLOWER FAMILY. 



485 



Bristles of the pappus in several series ; achenes somewhat 4-angled . . 



20. Cynara, p. 504. 

 Bristles of the pappus in a single series; achenes not angled 



21. Cirsium, p. 504. 



Filaments united below; pappus of narrow barbellate paleae 



22. Silybum, p. 509. 



Tribe 3. Senecioneae. Groundsel Tribe. 



Herbs, or two species suffrutescent. Leaves alternate or radical. 

 Bracts of the involucre little or not at all imbricated, mostly in 1 or 2 

 rows. Receptacle naked. Flowers of both disk and ray yellow, 

 except Petasites. Anthers not caudate. Pappus-bristles soft, com- 

 monly copious, most often white 



A. Radical leaves broad, palmately cleft or parted. 



Cauline leaves scale-like; flowers subdioecious, whitish; pistillate corollas 

 distinctly ligulate 23. Petasites, p. 509. 



Cauline leaves similar to the radical; flowers all perfect and fertile, 

 yellow; rays none 24. Cacaliopsis, p. 510. 



B. Leaves not palmately parted; flowers yellow. 



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

 white-woolly beneath 25. Litina, p. 510. 



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

 various . 



Leaves chiefly opposite; heads large 26. Arnica, p. 511. 



Leaves alternate; heads large or small 27. Senecio, p. 511. 



Tribe 4. Anthemidese. Mayweed Tribe. 



Strong-scented 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. Receptacle naked or with chaff- 

 like bracts. Flowers white, yellow or greenish. Kays 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, p. 514. 



Heads in a terminal corymb; rays 4 or 5; perennial 



29. Achillea, p. 514. 



B. Receptacle naked. 

 All of the flowers with a corolla. 

 Heads solitary, terminating leafy branches or peduncles. 



Rays many, conspicuous 30. Chrysanthemum, p. 515. 



Rays none; flowers all alike, perfect, greenish ; annual 



31. Matricaria, p. 515. 

 Heads corymbose; rays none; flowers yellow; perennial 



32. Tanacetum, p. 515. 

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



or purplish ; shrubs or herbs 33. Artemisia, p. 516. 



Marginal flowers without a corolla; heads discoid. 

 Heads peduncled; mature achenes bonu' on pedicels; style deciduous . . 



34. Cotula, p. 517. 



Heads sessile; achenes pointed with the spine-like persistent stvle .... 



35. Soliva, p. 518. 



