169 
+ + Involucre of one or more rows of separate bracts. 
+ Chaff of the convex or conical receptacle permanently investing the achenes as 
an indurated accessory covering. 
55, Sclerocarpus. Ray-flowers several and neutral: involucral bracts more or 
less herbaceous, the outer loose and spreading: pappus a short crown or ring, or 
none: branching herbs. 
++++ Chaff of the flat receptacle bristle-shaped. 
56. Eclipta. Ray short: involucral bracts 10 to 12 in 2 rows, herbaceous: pappus 
none, or sometimes 2 to 4 teeth or short awns. 
++++++ Chaff scale-like, embracing or subtending the achenes. 
= Rays none, the flowers all perfect and fertile: involucre dry or partly so; achenes 
not flat or margined: pappus of slender awns or none, 
57. Varilla. Achenes linear-oblong, terete, 8 to 15-nerved, with setulose pappus 
or none: shrubby or suffruticose, 
58. Isocarpha. Achenes 4 or 5-angled, small, destitute of pappus: herbaceous. 
= = Rays present (occasionally wanting in some genera): involucre commonly her- 
baceous, or partly so. 
a, Receptacle from conical to columnar or subulate (at least in fruit).--A species 
of Gymnolomia may be sought here. 
(1) Rays fertile (not rarely wanting): leaves opposite. 
59. Spilanthes. Involucre of few somewhat herbaceous loosely appressed bracts: 
achenes of ray 3-sided or compressed ; of disk more or less compressed with acute or 
nerve-like margins: pappusa slender awn from one or more of the angles, or none. 
(2) Rays sterile: leaves mostly alternate. 
60. Echinacea. Rays rose-colored, pistillate, sterile: achenes short, 4-sided: 
chaff spinescent. 
61. Rudbeckia. Rays neutral: achenes 4-sided, flat at top, marginless. 
62. Lepachys. Rays few, neutral: achenes flattened laterally and margined., 
b. Receptacle from flat to convex (in some species conical): achenes not winged or 
very flat, when flattened not margined or sharp-edged., 
(1) Rays fertile: pappus a toothed cup or crown. 
63. Borrichia. Achenes acutely 3 or 4-angled: chaff concave and rigid: shrubby. 
(2) Rays sterile (rarely wanting): chaff strongly concave or conduplicate and em- 
bracing the achenes, 
64. Gymnolomia. Pappus none or a minute denticulate ring. 
65. Viguiera. Pappus of two chaffy awns or scales (occasionally 1 or 2 more), 
and 2 or more intermediate truncate scales, either persistent or deciduous; achenes 
commonly pubescent. 
66. Helianthus. Pappus promptly deciduous, of two scarious and pointed scales, 
mostly no intermediate scales: achenes usually glabrous or glabrate. 
(c) Receptacle flat or convex (sometimes becoming conical): achenes of disk either 
flat and margined or thin-edged, or if turgid some of them winged: pappus not 
eaducous. 
(1) Shrubby, rayless, alternate-leaved ; achenes wingless. 
67. Plourensia. Involucre of 2 or 3 series of oblong or lanceolate bracts: recep- 
tacle flat: its chaff conduplicate around the achenes, which are compressed, callous- 
margined, very villous: puppus a slender somewhat chaffy awn from each angle of 
the truncate summit; and commonly some intermediate smaller ones. 
(2) Herbaceous (sometimes shrubby): rays neutral, rarely wanting: mature achenes 
wingless, the margins either villous-ciliate or naked. 
68. Encelia. Pappus none, or an awn or its rudiment, with no intermediate 
scales. 
