COMPOSITE.* 



CHARLES F. MILLSPAUGH AND AGNES CHASE. 



Herbs, shrubs, woody climbers, or rarely trees. Flowers perfect, 

 pistillate, neutral, or monoecious or dioecious, borne on a common 

 receptacle forming heads, subtended by an involucre of few to many 

 bracts. Calyx tube completely adnate to the ovary, the limb (pappus) 

 of bristles, awns, scales, teeth, or crownlike or obsolete. Corollas 

 tubular or expanded into a ligule; heads composed of tubular flowers 

 (discoid], of tubular and ligulate (radiate), or all ligulate (ligulate). 

 Stamens usually 5, borne on the corolla and alternate with its lobes, 

 their anthers united into a tube, often appendaged at the apex, some- 

 times sagittate or tailed at the base. Ovary i-celled; ovule i, anatro- 

 pous; style of fertile flowers 2-cleft; stigmas marginal; style of sterile 

 flowers commonly undivided. Fruit an achene. Seed erect; endo- 

 sperm none. 



ACHENE ENCLOSED IN A FALSE PERICARP. 

 Pericarp spinous: 



i -seeded Ambrosia. 



2-seeded Xanthium. 



Pericarp verrucose, obconical Nocca. 

 rhomboidal: 



achene lenticular Sclerocarpus. 



triangular Melampodium. 



Pericarp smooth Milleria. 



ACHENE NOT ENCLOSED. 

 Corolla of ray flowers persistent: 



Achenes all dorsally compressed Parthenium. 



Achenes laterally compressed or tri- / 



angular \ Sanvitalia, 



Corolla of disk flowers persistent Grindelia. 



Corollas all deciduous: 

 Pappus none at maturity: 



achene oblong Artemisia. 



achene obovoid: 



io-12-ribbed Flaveria. 



5-ribbed Isocarpha. 



4-ribbed Elvira. 



not ribbed Helianthus. 



achenes cuneate: 



imperfectly lenticular Achillea. 



quadrilateral: 



apex depressed Montanoa. 



apex coronate Amellus. 



apex bicornuate Eclipta. 



Pappus coroniform: 



crown minute, entire Alomia. 



crown prominent, 4-toothed Borrichia. 



Pappus a crateriform disk Baltimora. 



*The cuts present a portion of the inflorescence or a single head natural size, unless otherwise 

 indicated; the achene magnified (the natural size being indicated by a cross giving both diameters, 

 the dotted line representing the pappus); and a cross-section of the achene at its greatest diameter. 



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