POLYMNIA. COMPOSITE. 371 



Tribe IV. SENECIONIDEJE. Less. 



Heads heterogamous or heterocephalous {dioscious or monoecious). Style {in the perfect 

 jiowers) cylindraceous above ; the branches linear, somewhat pencillate or hairy at the 

 apex, either truncate or produced beyond the pencillum into a hairy cone ; the stigmatic 

 lines terminating in the base of the cone or appendage, not confluent. — Leaves opposite 

 or alternate. 



CONSPECTUS OF THE SUBTRIBES. 



Subtribe I. MELiMPODiNEi:. Flowers diclinous: the staminatc and pistillate either occupying the same or different 



heads, in the same or diflerent plants. 

 Subtribe II. Helianthe.s:. Heads heterogamous and radiate, or homogamous and discoid. Receptacle partly or en- 

 tirely chaffy. Pappus none or coroniform, or awned. Anthers blackish, without tails. — Leaves often 



opposite. 

 Subtribe III. Helenie^e. Heads mostly heterogamous. Pappus consisting of numerous distinct scarious chaffy scales 



in a single series, rarely wanting. — Leaves mostly alternate. 

 Subtribe IV. A.vtiiemideje. Heads mostly heterogamous. Anthers not caudate. Pappus none or coroniform, rarely 



consisting of scales. Branches of the style truncate and bearded at the apex, rarely terminated by a 



conical point. — Leaves mostly alternate. 

 Subtribe V. Gnaphalie.1:. Heads homogamous and discoid, or rarely heterogamous. Anthers caudate. Pappus 



capillary or setaceous, rarely wanting. — Leaves mostly alternate. 

 Subtribe VI. Seneciones:. Heads homogamous or heterogamous, discoid or radiate. Anthers not caudate. Pappus 



capillary, or rarely wanting in the exterior flowers. — Leaves alternate. 



Subtribe I. MelampodinEjE, DC. Flowers diclinous {none of them perfect) ; the pistillate 

 and staminate either on different plants {dioscious), or in different heads of the same 

 plant {heterocephalous), or in different f.owers of the same head {monoecious). Anthers 

 not caudate at the base. Receptacle almost always chaffy. Pappus none or somewhat 

 coroniform, never consisting of bristles. \ 



CONSPECTUS OF THE GENERA. 

 * Heads monoecious. 



16. PoLYMNlA. Heads radiate. Achcnia obovoid, not winged. 



17. SiLPHrcM. Heads radiate ; the ray deciduous. Achenia winged, in more than one series. Pappus of 2 teeth or 



short awns. 



18. IvA. Heads not radiate, bracteate. Anthers scarcely united. Receptacle chaffy. Flowers smooth. 



** Heads heterocephalous, not radiate. Anthers distinct. 



19. Ambrosia. Fertile involucre 1-cellcd, l-flowcreil, not spinous throughout. 



20. Xanthid-m. Fertile involucre 2-celled ; the scales of the sterile distinct. 



16. POLYMNIA. Linn. ; DC. prodr. 5. p. 514 ; Endl. gen. 2475. LEAF-CVP. 



[Pohmnia is the name of one of the Muses; but we know not why Linnoius appUed it to this homely genus.] 



Heads many-flowered ; the ray-flowers few, pistillate ; those of the disk tubular, sterile. 

 Scales of the involucre in a double series ; the exterior 4-5, large and foliaceous ; the 

 interior smaller, membranaceous, partly embracing the achenia. Receptacle chaflfy, flat. 



47* 



