THISTLE FAMILY 837 



Receptacle not chaffy; style or style-branches of the hermaphrodite flowers mostly 

 truncate. 

 Plants dioecious, or the pistillate heads with a few hermaphrodite flowers in the 

 center. 

 Pappus-bristles of the pistillate flowers falling off in a ring ; central hermaph- 

 rodite flowers none. 55. Antexnaria. 

 Pappus-bristles of the pistillate flowers falling off separately; central hermaph- 

 rodite flowers present in the pistillate heads. 56. An.^.phalis. 

 Plants not dioecious; flowers fertile tlu'oiighout the heads, hermaphrodite in the 

 middle, surrounded by pistUlate ones. 57. Gnaphaltum. 



Tribe 5. ADENOCAULEAE. 

 Leaves cordate, white-wooUy beneath. 58. Adenocaulon. 



Tribe 6. HELIANTHEAE. 

 A. Bracts (at least the outer series) not enclosing the achenes of the rays; plants not 

 glandular-viscid. 



I. Disk-flowers hermaphrodite but sterile. 



Marginal pistillate flowers, with conspicuoiis rays. 



Achenes not flattened; Hgules in ours white; involucres of very dissimilar sets 



of bracts. 59. IMel.\mpodium. 



Achenes flattened; Ugules in ours yellow. 



Ray-flowers in 2-3 series; achenes faUing away free. 



60. SILPHITJM. 



Ray-flowers in 1 series; achenes adnate to 2 or 3 paleae and falling away 

 with them. 61. Engeolaxxla. 



Marginal pistiUate floweis reduced to a truncate or obhquely-cleft tube; the 

 hgules, if any, reduced to 2 or 3 smaU teeth. 

 Acaulescent cespitose perennials; pappus of a parr of lanceolate membranous 



scales. 62. Bolophyta. 



Caulescent annuals; pappus none. 63. P.vrthexice. 



II. Disk-flowers fertile. 



a. Ray-flowers fertile; the Ugules with very short tube, persistent on the achenes 



and becoming papery in texture. 

 Achenes of the disk compressed ; leaves entire. 64. Cr.\ssina. 



Achenes obtusely 4-angled. 



Leaves toothed; paleae pointless, partly enclosing the achenes. 



65. HEiJoreis. 

 Leaves entire ; paleae linear-lanceolate, not enclosing the achenes. (§ Ka Uiac- 

 tis, i. e.. B. Carcyana, of) 71. Balsamorrhiza. 



b. Ray-corollas deciduous from the achenes or wanting. 



1. Pappus a crown or none, or of a few squamellae on the angles of the achenes, 

 and rarely minute ones between. 

 a. Achenes of the disk-flowers not obcompressed (except in Ratibida and 

 Ximenesia): paleae usually more or less concave and clasping. 

 Receptacle conic, subulate or columnar. 

 Achenes 4-angled. 



Ray-flowers purphsh or rarely wliitish: disk-corollas almost 



without a tube; pappus coroniform. 66. Brauxeria. 

 Raj--flowers yeUow or none; disk-coroUas with a short but mani- 

 fest tube. 

 Achenes quadrangular-compressed; apex of the achenes 

 covered by the base of the corolla-tube. 



67. GYMX0IX)MIA. 



Achenes nearly equally 4-angled; apex not covered by the 

 base of the corolla. 68. Rudbeckia. 



Achenes 5-angled; ray -flowers white. 70. Galinso'GA. 



Achenes flattened, broad-margined or winged. 



69. Ratibida. 

 Receptacle from flat to convex. 



Achenes of the disk neither sharp-angled, margined, nor winged. 

 Rays fertile, their achenes commonly 3-angled or obcompressed : 

 plants with thick balsamiferous taproots. 

 Pappus none; stem scapiform or with reduced leaves. 



71. Balsamorrhiza. 

 Pappus a lacerate chaffy crown or of distinct squamellae: 

 stem low but leafy. 72. Wyethia. 



Rays sterile or wanting: plants not with fleshy taproot. 

 Pappus none or a minute ring. 67. Gtmxolomia. 



Pappus of 2 scarious awns. 73. Heliaxthus. 



Achenes of the disk thin-edged, margined or winged. 

 Ray-flowers neutral; achenes scarcely winged. 



Pappus none or an awn to each angle of the achenes. 



74. Excelia. 

 Pappus of small teeth between the 2 or more awns or scales 



over the angles of the achenes. 

 Plants scapose; achenes with a callous margin. 



75. EXCELIOPSIS. 



Plants caulescent; achenes not margined. 



76. Heliaxthella. 



