1907] Hall. Compositae of Southern California. 13 



such heads are said to be radiate. Heads without ligulate corol- 

 las are said to be discoid. The term ray is sometimes used for 

 ray-corolla, sometimes for only the ligule of the ray-corolla. 

 Ray-flowers commonly pistillate, sometimes perfect or neutral: 

 disk-flowers commonly perfect, often staminate or pistillate. 

 Heads homogamous, that is, with all their flowers alike; or 

 heterogamous, that is, with more than one sort of flowers. Homo- 

 gamous heads may have all the corollas ligulate, or they may be 

 discoid. Calyx-tube united with the ovary, the linib when present 

 called a pappus and greatly varied in structure, consisting of 

 awns, hairs, bristles, scales, or paleae, or in some cases appearing 

 as a mere crown or ring or wholly obsolete. Stamens 5 (rarely 

 4 or 3) inserted on the corolla-tube and alternating with its lobes 

 or teeth; anthers 2-celled, united and forming a tube, or nearly 

 or quite free in Ambrosieae, introrse, from obtuse to auriculate 

 or caudate (tailed) at base, usually appendaged above, this ap- 

 pendage being a prolongation of the connective between the 

 anther-cells. Style divided above into 2 branches which bear 

 stigmatic lines on their inner face. Ovary 1-celled, 1-ovuled. 

 maturing into an acliene, crowned by the pappus when that is 

 present. 



KEY TO THE TRIBES, 



A. Corollas all regular (the heads then discoid) or only the marginal 



ones ligulate (the heads then radiate). 

 Anthers not caudate at the base. 



Keceptacle naked (without bristles or chaffy bracts, except nos. 83 and 



84) ; leaves alternate (except in nos. 3, 59, 64, 65, 82, and 91). 

 Style-branches thickened upward, obtuse; stigmatic lines not ex- 

 tending beyond the middle: flowers never yellow: rays none... 

 1. EUPATOEIEAE, p. 14. 



Style-branches not thickened upward; stigmatic lines in perfect 



flowers extending to the summit. 



Bracts of the involucre usually imbricated : disk-flowers common- 

 ly yellow ; rays of the same or different color or none : 

 style-branches in perfect flowers flattened and with a dis- 

 tinct (but sometimes very short) terminal appendage 



2. ASTEREAE, p. 15. 



Bracts of the involucre in few series, seldom much imbricated: 

 disk yellow; rays often of the same color when present: 

 style-branches in perfect flowers with truncate or variously 

 appendaged tips 7. HELENIEAE, p. 21. 



