167 
++++ Pappus present and mostly similar in ray and disk. 
30. Aster. Heads many-flowered, on leafy peduncles: involucral bracts unequal, 
loosely or closely imbricated: achenes tlattish: pappus simple (rarely double), copi- 
ous. 
31. Brigeron. Heads many-flowered, on naked peduncles: involucre of narrow 
equal bracts, little imbricated: achenes flattened: pappus simple and rather scanty, 
or with some outer minute scales, 
** * Corolla of the numerous female flowers reduced to a filiform or short and nar- 
row tube, wholly destitute of ligule. 
32. Conyza. Heads small and many-flowered, with narrow involucral bracts in 
1 to 3 series: achenes amall and compressed: pappus a single series of soft capillary 
bristles, sometimes an added outer series, 
** * * Rays none: heads diwcious (all pistillate or all staminate), 
33. Baccharis. Heads many-flowered: pappus capillary : smooth glutinous shrubs. 
Tribe IV. INvLoipEa. Heads discoid, the pistillate flowers mostly filiform and 
truncate: anthers sagittate, the basal lobes attenuate into tails: style-branches with 
unappendaged obtuse or truncate naked tips: pappus capillary or none, 
“Receptacle naked: involucre not scarious, imbricated: not woolly, 
34, Pluchea. Heads containing a few perfect but sterile flowers in the center, 
and many pistillate fertile ones around them: involuere imbricated, the outer bracts 
broad, all but the innermost persistent: pappus capillary: heads cymosely clustered 
or scattered. 
35, Pterocaulon. Heads and flowers as in Pluchea, but involucre of fewer and 
linear or subulate bracts, which are deciduous with the matured flowers: heads 
glomerate and the glomerules spicate. 
** Receptacle chaffy: involucral bracts few, mostly scarious: low floccose- woolly 
annuals, 
36. Evax. Flowers as in Pluchea: achenes obcompressed : pappus none, 
** * Receptacle naked: involucral bracts many and scarious: floccose-woolly herbs. 
37. Antennaria. Heads diwcious: pappus of sterile flowers club-shaped, of the fer- 
tile united at base and deciduous together. 
38. Gnaphalium. Heads all fertile throughout: pappus all capillary. 
Tribe V. HELIANTHOIDE®, Heads radiate or discoid: involucre not scarious: 
receptacle chaffy: pappus never capillary, sometimes none: anthers not caudate: 
style-branches truncate or hairy-appendaged. 
* Heads radiate, the ray pistillate and fertile, the disk perfect but sterile. 
+ Involueral bracts in 2 rows, the inner embracing or inclosing the turgid or but 
little compressed achenes: pappus none. 
39. Polymnia. Involucre of about 5 outer loose leaf-like bracts, and as many or 
more numerous smaller and thinner inner ones embracing and half inclosing. the 
thick and turgid obovoid achenes. 
40. Melampodium. Involucre strongly dimorphous, the outer of 4 or 5 leaf-like 
plane bracts, the inner of a single series of small bracts which completely and _per- 
manently inclose the obovate or oblong more or less compressed achenes with a peri- 
carp-like accessory covering. 
+ + Involuecral bracts not inclosing or embracing the achenes, 
++ Involucre of 3 or 4 narrow bracts: achenes dimorphous, little if at all compressed, 
41, Dicranocarpus. Ray-flowers 3 or 4, with very small ligules: 1 or 2 achenes 
elongated to twice or thrice the length of the involucre, from subulate to oblong- 
linear, tipped with 2 diverging stout naked awns or horns; the others shorter, the 
truncate apex bearing a pair of very short divaricate horns or hardly any. 
