CARDUACEAE. 333 



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 tap-roots. 

 Pappus none ; stem scapiform or with reduced leaves. 



48. BALSAMORRHIZA. 

 Pappus a lacerate chaffy crown or of distinct chaffs ; stem 



low but leafy. 49. WYETHIA. 



Rays sterile or wanting ; plants not with fleshy tap-root. 

 Pappus none or a minute ring. 45. GYMNOLOMIA. 



Pappus of 2 scarious awns. 50. HELIANTHUS. 



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

 Ray-flowers neutral ; achenes scarcely winged. 



51. HELIANTHELLA. 



Ray-flowers fertile ; achenes winged. 52. XIMENESIA. 



b. Achenes obcompressed ; chaffs flat or hardly concave ; involucres 



distinctly double. 

 Bracts of the involucres distinct or nearly so. 



Pappus in ours of small teeth, a mere border, or wanting. 



53. COREOPSIS. 



Pappus of 2-4 barbed or hispid awns. 54. BIDENS. 



Bracts of the inner involucre united at least to near the middle. 



55. THELESPERMA. 

 2. Pappus of s-many, linear to lanceolate scales with thickened axis and 



hyaline margins. 74. GAILLARDIA. 



B. Bracts of the involucres uniserial, partly or wholly enclosing the achenes of 

 the fertile ray-flowers ; plants glandular-viscid. 56. MADIA. 



TRIBE 6. HELENIAE. 



A. Plant-tissues without oil-glands. 



I. Ligules persistent and becoming papery on the striate achenes ; plants more 

 or less woolly. 57. PSILOSTROPHE. 



II. Ligules deciduous or none. 



a. Achenes flat with only marginal nerves ; disk-corollas 4-toothed. 



58. PERICOME. 



b. Achenes angled, not flat, nerved or striate. 

 i. Receptacle naked. 



a. Bracts of the involucres pale or colored, at least the margins and 



tips scarious. 

 Corollas of the disk-flowers with reflexed or spreading lobes ; bracts of 



the broadly campanulate involucres obovate or broadly oblong. 

 Heads discoid. 59. HYMENOPAPPUS. 



Heads radiate ; ligules obscurely toothed, yellowish or white. 



60. LEUCAMPYX. 

 Corolla of the disk-flowers with linear, erect lobes : bracts of the 



turbinate involucres spatulate to linear-oblanceolate in two series ; 

 heads in our species radiate ; ligules deeply cleft, purple. 



61. POLYPTERIS. 



b. Bracts of the involucres neither colored nor scarious. 

 Achenes 4-angled. 



Foliage impressed punctate ; leaves, at least the lower, opposite. 

 Perennials, suffruticose at the base ; leaf-segments oblong to 



linear. 62. PICRADENIOPSIS. 



Annuals ; leaf-segments filiform or nearly so. 



63. ACHYROPAPPUS. 



Foliage not impressed-punctate : leaves alternate. 

 Bracts obovate, cuneate or oblanceolate. 



Perennials with a woody caudex ; leaves entire; pappus of 10 



scales. 64. PLATYSCHKUHRIA. 



Annuals ; leaves dissected ; pappus in our species wanting. 



65. BAHIA. 

 Bracts linear. 66. CHAENACTIS. 



