Composita.] composite. 165 



Order LIX. COMPOSITE. 



Flowers ox florets collected together into a head surrounded by an involucre 

 of several bracts, either in one row or imbricated in several rows, the whole 

 having the appearance of a single flower. Eeceptacle on which the florets are 

 inserted either naked or bearing chaffy scales or hairs or bristles between the 

 florets. In each floret the calyx is wanting, or converted into a pappus or 

 ring of hairs or scales on the top of the ovaiy. Corollas either all herma- 

 phrodite tubular and 5- or rarely 4-toothed (heads discoid), or all hermaphro- 

 dite and ligulate, or those of the centre or disk tubular and hermaphrodite or 

 male, and those of the circumference ligulate, forming a ray (heads radiate), 

 or filiform and female. Stamens 5, inserted in the tube of the corolla; the 

 anthers linear and united in a sheath round the style (except in Xanthium), 

 often sagittate at the base, the basal lobes sometimes prolonged into fine 

 points called tails. Ovary inferior, with a single erect ovule. Style filiform, 

 usually divided at the top into two short stigmatic branches. Fruit a small 

 dry nut or achene, crowned by the pappus or naked. — Herbs or shrubs, with al- 

 ternate or opposite leaves, without stipules. 



The most extensive family among flowering plants, and represented in every quarter of the 

 globe, and in every variety of station. In the following table the genera are, for convenience of 

 reference, classed under artificial groups, not always corresponding with the tribes charac- 

 terized in the text. 



§ 1. Heads homogamous, the florets all tubular and hermaphrodite. 



Leaves alternate. 



Heads many-flowered. Florets regular. 

 Involucre imbricate, in 2 or more rows. 

 Pappus of numerous plumose bristles. 



Leaves and usually the outer involucral bracts prickly . 2. Cirsium. 



Leaves not prickly 1. Saussurea. 



Pappus of numerous capillary bristles 3. Vernonia. 



Involucre of 10 to 15 equal bracts in one row. 



Involucre surrounded by smaller bracts at the base. 



Style-branches with long points 32. Gynura. 



Involucre without outer bracts. Style-branches obtuse . 33. Senecio. 

 Heads 2- to 5 -flowered. Florets slightly irregular. 



Flower-heads clustered into compound heads, with a general 



involucre. Pappus of stiff awns or scales 4. Elephantopus. 



Flower-heads solitary, in a long spike. Pappus of plumose 



bristles 36. Ainsli^a. 



Leaves opposite. 



Receptacle naked. Achenes short. 



Pappus of 3 to 5 short bristles, each tipped by a gland . . 5. Adenostemma. 

 Pappus of 5 to 10 stiff bristles, chaffy or dilated at the base . 6. Ageratum. 



Pappus of numerous capillary bristles 7- Eupatorium. 



Receptacle bearing scales between the florets. Achenes long, 



with 2 to 5 stiff retrorsely hispid awns 24. Bidens. 



§ 2. Flower-heads discoid, but heterogamous. Florets of the circumference slender and 

 female, those of the disk tubular and hermaphrodite or male. Leaves alternate. 



Pappus of numerous capillary bristles. 



Florets of the circumference few, in 1 or 2 rows. Disk-florets 



numerous. Anthers with double tails . . 17- Inula. 



