1402 CONTEIBUTIONS FEOM THE NATIONAL HERBARIUM 



ligulate or strap-shaped, bilabiate, tubular, and filiform. Heads composed of one 

 kind of flowers only are called homogamous, those composed of two or more kinds 

 heterogamous; when heterogamous, the central flowers (disk) are always herma- 

 phrodite, the peripheral pistillate or neutral (lacking the style). Homogamous 

 heads in which all the flowers are hermaphrodite and have ligulate (in this case 

 always 5-toothed) corollas are called ligulate; homogamous heads in which all the 

 corollas are tubular and hermaphrodite or staminate, or filiform and pistillate, 

 are called discoid. Heterogamous heads in which the peripheral corollas are 

 ligulate are called radiate; those in which the peripheral flowers are pistillate, 

 with tubular, filiform, or abortive corollas are called disciform. The receptacle 

 may be naked, bristly, or paleaceous (bearing pales or chaff). The generic 

 characters are drawn to a considerable extent from the character of the pappus, 

 which may be of bristles, awns, scales, or teeth, or reduced to a crown or cup, or 

 entirely wanting. 



KEY TO TRIBES. 



Anthers caudate at base. 

 Corollas all bilabiate, or else (Gochnatia) the involucre of graduate indurate 



phyllaries . IX. Mutisieae. 



Corollas tubular or filiform; involucre not of indurate phyllaries-IV. Inuleae. 

 Anthers not caudate at base. 



Style branches elongate, acute, hispidulous outside throughout their length. 



Heads yellow VIII. Senecioneae. 



Heads white or purplish, never yellow. 



Achenes not 4-angled and clavate; pappus not consisting of paleae with 



a strong midrib I. Vernonieae. 



Achenes 4-angled, clavate; pappus consisting of paleae with a strong 



midrib VI. Helenieae. 



Style branches otherwise. 



Style branches usually elongate, linear or clavate, obtuse, not hispidulous 

 outside or at apex, the stigmatic lines only below the middle and 



inconspicuous; heads never yellow II. Eupatorieae. 



Style branches, when elongate, hispidulous outside or at apex, the stigmatic 

 lines reaching nearly to apex; heads often yellow. 

 Phyllaries scarious-margined; heads nodding, small, discoid or disciform; 



style tips truncate, hispidulous VII. Anthemideae. 



Phyllaries not scarious-margined, or else heads not nodding or style tips 

 acute. 

 Receptacle paleaceous, at least in the staminate heads, or else leaves 

 chiefly or entirely opposite; pappus not of bristles. V. Heliantheae 

 Receptacle not paleaceous (rarely bristly), or else leaves alternate. 

 Pappus present, chiefly or entirelj^ of soft capillary bristles; involucre 

 not glandular-punctate. 



Style tips acute III. Astereae 



Style tips truncate or subtruncate VIII. Senecioneae. 



Pappus wanting or of squamellae, awns, or stiff bristles, or else in- 

 volucre glandular-punctate. 

 Leaves alternate (opposite in one species of Aplopappus). 



III. Astereae. 

 Leaves opposite at least below or else involucre glandular-punctate. 

 (Exceptions are Venegasia, with large triangular-ovate leaf 

 blades; C'lappia, with densely setose-fimbrillate receptacle; 

 Psilostrophe, with papery -persistent ligules; Chaenactis, with 

 discoid ochroleucous heads and a pappus of about 13 long 

 paleae) VI. Helenieae. 



