COMPOSITE 333 



of 20 long-plumose bristles. On high stony hills, near Stein mountain 

 southeastern Oreg- n. 



Tribe iv Helianthoidese B. & H. Gen. ii, 166. Heads heterog- 

 amous and the pistillate flowers ligulate and radiate, or rarely with 

 corolla wanting, and then sometimes monwcious: or sometimes homo- 

 famous by the absence of the ray-flowers: disk- flowers all with regular 

 Jf-5-toothed tubular corolla. Receptacle usually with palese or chaff 

 subtending either all the flowers or the marginal ones only. Anthers 

 at most sagittate, not caudate at base. Style-branches of the herma- 

 phrodite or sterile flowers truncate or continued into a hairy conical 

 to subidate appendage. Pappus various or none: never of truly cap- 

 illary bristles. 



Subtribe i Ive.e. Heads androgynous, having few fertile 

 flowers at the margin. 



35 Iva Fertile flowers 1-5, with or without the tube or cup representing 

 a corolla 



Subtribe ii, Ambrosie^e. Heads homogamous, monoecious : 

 the fertile ones with 1-4 apetalous flowers in a closed bur-like or 

 achene-like pointed involucre ; the sterile with numerous flowers 

 in an open involucre. 



* Involucre to the staminate flowers 5-12 lobed or almost truncate 



36 Ambrosia Fertile involucres 1-flowercd, achene-like, bearing no more 

 than one row of tubercles or short spines. 



37 Gsertneria Fertile involucres 1-4-flowered, 1-4-celled, armed with 

 more than one row of tubercles or prickles. 



* * Involucre of the staminate heads of a few distinct scales 



38 Xanthium Fertile involucres bur-like, 2-celled, 2-flowered, beset with 



with numerous hooked prickles. 



Subtribe hi Verbesine^e Heads radiate with either neutral 

 or pistillate ray flowers or rayless : the disk-flowers perfect and 

 fertile. Receptacle chaffy. Achenes thick and 3-4-angled or 

 those of the disk laterally compressed. 



* Receptacle elongated, becoming columnar. 



39 Rudbeckia Rays neutral or rarely wanting : achenes quadrangular 



and compressed. 



* * Receptacle flat , concave or rarely conical; 



•*- Rays pistillate and fertile. 



40 Balsamorhiza Pappus none : achenes of the ray obcompressed ; of the 



disk prismatic-quadrangular or somewhat compressed. 



41 Wyethia Pappus a chaffy-coriaceous crown or cup, continuous with 

 the broad summit of the achene . 



-*- +- Rays neutral, rarely wanting. 



42 Helianthella Achenes flat, the thin edges more or less wing-like : 

 pappus a pair of persistent awns or chaffy teeth and a crown of inter- 

 mediate chaffy r-cales. 



