SUNFLOWER 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. 

 Rays 5 to 40, 2 or 3-lobea or -toothed; disk-achenes with or without pappus ; 

 leaves, at least at base, not 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. Hemizonia, p. 520. 



Receptacle convex; rays about 15, 3-lobed; bracts of involucre and of 

 receptacle persistent, the outer beset with clavate processes .... 



48. Holocarpha, p. 531. 

 Leaves (at least the upper) spinose 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. Centromadia, p. 532. 

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

 pappus; leaves all narrowly linear and entire 



50. Calycadenia, p. 533. 

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



51. Blepharizonia, 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. Blepharipappus, 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; heads solitary; bracts of receptacle connate; flowers white 



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



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

 scarious, the longer set of palese longer than the achenes 



55. ACHYRACH^NA, p. 539. 



Tribe 7. Heliantheae. Sunfloweb Tribe. 



Herbs with mostly opposite or radical leaves. Herbage commonly 

 with balsamic-resinous juice. Rays 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. 540. 

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

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



Pappus none 57. Balsamorrhiza, p. 540. 



Pappus present 58. Wyethia, 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. Helianthtjs, p. 542. 

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

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



