216 COMPOSITE, (composite family.) 



tacle among the flowers, are called the chaff: -when these are wanting, 

 the receptacle is said to be naked. — The largest order of Phfenogamous 

 plants. It is divided by the corolla into three suborders, only two of 

 which are represented in the Northern United States. The first is much 

 the larger. 



Suborder I. TIJBirL.IFLOB^. 



Corolla tubular in all the perfect flowers, regularly 5- (rarely 3 - 4-) 

 lobed, ligulate only in the marginal or ray-flowers, which when present 

 are either pistillate only, or neutral (with neither stamens nor pistil). 



The technical characters of the five tribes of the vast suborder Tubuliflorce, 

 taken from the styles, require a magnifying-glass to make them out, and will 

 not always be clear to the student. The following artificial analysis, founded 

 upon other and more obvious distinctions, will be useful to the beginner. (The 

 numbers are those of the genera.) 



Artificial Key to the Genera of this Suborder. 



§ 1. Rays or ligulate flowers none : corollas all tubular (or rarely none). 

 * Flowers of the head all perfect and alike* 

 Pappus composed of bristles ; 

 Double, the outer of very short, the inner of longer bristles. .... No. 1. 



Simple, the bristles all of the same sort. 

 Heads few-flowered, themselves aggregated into a compound or dense cluster. . 2. 



Heads separate, few-flowered or many-flowered. 

 Receptacle (when the flowers are puUed off) bristly-hairy . . . 67, 68, 70. 



Receptacle deeply honeycomb-like. . . 69. 



Receptacle naked. 

 Pappus of plumose or bearded stiff bristles. Flowers purple. . . . . 4. 



Pappus of very plumose bristles. Flowers whitish. ... • . 5. 



Pappus of slender but rather stiff rough bristles 6, 7, 8, 20. 



Pappus of very soft and weak naked bristles 62, 63. 



Pappus composed of scales or chaff. 

 Receptacle naked. Leaves in whorls. ... . . . . 3> 



Receptacle naked. Leaves alternate. .... .45. 



Receptacle bearing chaff among the flowers. 49. 



Pappus of 2 or few barbed awns or teeth .... 41, 42. 



Pappus none, or a mere crown-like margin to the fruit. 55, 57- 



* * Flowers of two kinds in the same head. 

 Marginal flowers neutral and sterile, either conspicuous or inconspicuous. . . 65, 66. 

 Marginal flowers pistillate and fertile. 



Receptacle elongated and bearing broad chaff among the flowers 60. 



Receptacle naked or bearing no conspicuous chaff. 

 Pappus of capillary bristles. Involucre imbricated. . . ... 23, 58, 59 



Pappus of capillary bristles. Involucre merely one row of scales. . . .14, 61. 



Pappus obsolete or none. 



Achenia becoming much longer than the involucre. 11. 



Achenia not exceeding the involucre, . . .... 29, 56, 57. 



* *** Flowers of two kinds in separate heads, the one pistillate, the other staminate. 

 Heads dioecious ; in both kinds many-flowered. Pappus capillary. . . . 24, 59. 



Heads monoecious ; the fertile 1-2-flowered and closed. Pappus none. . . . 30, 31. 



