232 COMPOSITE, (composite family.) 



♦♦ ++ Receptacle flat or convex. Pappus usually with awns. 



21. Chaetopappa. Achenes fusiform ; pappus of 5 or fewer thin cliaSf and alternating 



awns. Western. 



22. Boltonia. Achenes very flat, thick-winged ; pappus of short bristles and usually 2-4 



awns, 

 -t- -t- Pappus of a single row of awns or coarse rigid bristles, or in the ray scale-like. 



23. Townsendia. Low or stemless, with linear-spatulate leaves and large aster-like flowers. 



-I- -1- -K- Pappus of numerous long and capillary bristles ; receptacle flat. 



24. Sericocarpus. Heads 12 - 20-flowered ; rays 4 or 5. Involucre oblong or club-shaped, 



imbricated, cartilaginous. Achenes sliort, narrowed downward, silky. 



25. Aster. Heads many-flowered, on leafy peduncles. Involucral scales unequal, loosely 



or closely imbricated. Achenes flattish ; pappus simple (rarely double), copious. 



26. Erigeron. Heads many-flowered, on naked peduncles. Involu(^-e of narrow equal 



scales, little imbricated. Achenes flattened ; pappus simple and rather scanty, or 

 with some outer minute scales. 



* 3. Rays none. Heads dioecious (all pistillate or all staminate). 



27. Baccharis. Heads many-flowered. Pappus capillary. Smooth glutinous shrubs. 



Tribe IV. INUL.OIDE.aE. Heads discoid (radiate only in Inula), the pistillate flowers 

 mostly filiform Hud truncate. Anthers sagittate, the basal lobes attenuate into tails. 

 Style-branches with unappendaged obtuse or truncate naked tips. Pappus capillary 

 or none. 



* 1. Receptacle naked. Involucre not scarious, imbricated. Not woolly. 



28. Pluchea. Heads containing a few perfect but sterile flowers in the centre, and many 



pistillate fertile ones around them. Pappus capillary. 



• 2. Receptacle chafl'y. Involucral scales few, mostly scarious. Low floccose-woolly 



annuals ; flowers as in n. 28. 



29. Evax. Receptacle convex. Achenes obcompressed. Pappus none. Western. 



30. Filago. Receptacle subulate. Achenes terete. Outer flowers without pappus. 



* 3. Receptacle naked. Involucral scales many, scarious. Floccose-woolly herbs. 



31. Antennaria. Heads dioecious. Pappus of sterile flowers club-shaped, of the fertile 



united at ba.se and deciduous together. 



32. Anaphalis. Heads dioecious or nearly so. Pappus not thickened above nor at all 



united at base. 



33. Gnaphalium. Heads all fertile throughout. Pappus all capillary. 



* 4. Corollas all somewhat broadly tubular and lobed. Involucre not scarious. Receptacle 



naked. Pappus none. 



34. Adenocaulon. Head few-flowered and scales few ; outer flowers pistillate. Some- 



what woolly. 

 * 5. Heads radiate. Receptacle naked. Involucre herbaceous. Pappus copious. 



35. Inula. Heads large, many-flowered. Flowers yellow. Stout perennial. 



Tribe V, HEIilANTHOIDE.^. Heads radiate or discoid. Involucre not scarious 

 (nut-like in fruit in n. 43, 44). Receptacle chafl'y. Pappus never capillar}', sometimes 

 none. Anthers not caudate. Style-branches truncate or hairy-appendaged. 



m 1. Heads radiate (obscurely so in n. 41, sometimes discoid in n. 36), the ray pistillate and 

 fertile, the disk perfect but sterile. 



■i- Achenes turgid, triangular-obovoid ; pappus none. 



36. Polymnia. Involucral scales in 2 rows, the 5 outer leaf-like, the inner small. 



H- -t- Achenes flattened dorsally (obcompressed). 



37. Silphium. Achenes wing-margined, in several rows ; pappus none or 2 teeth. Scales 



thick, in several rows. 



