ST'NFLOWER FAMILY. 487 



B. Ray-achenes turgid or somewhat obcompressed, half enclosed by the 



bracts of the Involucre which are rounded on the back. 

 Achenes of ray without pappus. 

 Says 6 to 40, 2 orS-lobed or -toothed; disk-achenes with or without pappus; 

 leaves, at least at base, uot entire. 

 Leaves not spiny, commonly viscid and glandular. 

 Receptacle flat; rays 5 to 25, always (?) 3-lobed; bracts of involucre and 



of receptacle at length deciduous 47. Hemizojiia, p. 529. 



Receptacle convex: rays about ]5, 3-lobedj bracts of involucre and of 

 receptacle persistent, the outer beset with clavate processes . 



48. HOLOCAEPHA, p. 531. 



Leaves (at least the upper) spiuose and rigid, little viscid or glandular; 

 rays 25 to 40, 2-lobed; bracts of involucre and of receptacle persistent 

 or deciduous, not beset with processes . . 49. Centbomadia, p. 532. 

 Rays 1 to 5 (or 8), broad and palmately 3-lobed; achenes with paleaceous 

 pappus; leaves all narrowly linear "and entire 



50. Calycadbnia, p. 533. 

 Achenes of ray with pappus; disk-achenes with plumose pappus 



51. Blephasizonia, p. 534. 



C. Ray-achenes obcompressed or clavate, completely enfolded by the 



bracts of the Involucre, which at base have thin margins 

 and flattish backs. 



Achenes in fruit not expanding; pappus present or none. 

 Vernal annuals; rays 8 to 20, commonly showy, yellow, white, or yellow 



tipped with white 52. Blephabipappus, p. 535. 



Summer plants ; rays 5, comparatively inconspicuous. 

 Annuals; heads clustered; bracts of receptacle distinct; rays pale yel- 

 low; pappus none 53. Lagophylla, p. 538. 



Perennial; neads solitary; bracts of receptacle connate; flowers white 



or rose-tinged ; pappus present 54. Holozoni A, p. 539. 



Achenes in fruit expanding into an open globose head; pappus silvery- 

 scarious, the longer set of palese longer than the achenes 



55. ACHYEACHi:NA, p. 539. 



Tribjs 7. Heliantheae. Si'xflowee Tribe. 



Herbs with mostly opposite or radical leaves. Herbage commonly 

 with balsamic-resinous juice. Bays present, almost always showy. 

 Bracts of the involucre herbaceous or foliaceous, or at least not 

 scarious. Receptacle with chaff-like bracts, each subtending a flower. 

 Anthers not caudate. Pappus paleaceous, of rigid awns, or cup-like, 

 never of capillary bristles. Achenes thick or flattened contrary to 

 the subtending chaffy bract, never parallel with it. 



A. Bracts of the involucre in 2 to several series. 

 Involucre of 2 series of similar bracts; flowers' white; leaves opposite.. . 



56. ECLIPTA, p. 640. 

 Involucre imbricated, its bracts in several series; flowers yellow. 

 Ray-flowers maturing achenes; low perennials with broad radical leaves. 

 Pappus none. . . . . . . .57. Baisamokrhiza, p. 540. 



Pappus present .58. Wybthia, p. 541. 



Ray-flowers not maturing achenes. 

 Pappus persistent; achenes thick, not notched at summit; leaves alter- 

 nate, except the lowest; tall annuals or perennials 



59. Helianthus, p. 542. 

 Pappus caducous; achenes compressed, notched at apex; leaves chiefly- 

 or all radical; perennial 60. Heijanthella, p. 543. 



