COMruSiTE FAMILY. 227 



II II Flowers ii'hitish. 

 30. PARTHENIUM. Heads small, many-flowered; the rays 5, usually inconspicuous, 



with very short and broad obcordate limbs not projectinjr beyond the woolly disk. 



Involucre hemi.sphericiil, with two rows of short or roundish scales. Akenes ob- 



compros.sed, with a slender callous margin, crowned with the ijcrsi.stiii','- r.iy corolla 



and the pajjpus of two small chatty scales. 

 ^ = Diskjloirergper/eri and fertile, those of the ray pistillate and fertile, or neutral. 



(Ciutaitrea may be sought here; see p. 22'2.) 

 II Ahenes flattened parallel with the scales of the involucre and chaff of the receptacle, 



or in 44 sometimes reri/ slender. Leaves generally opposite; involucre double, 



the outer mostly leafy like, the inner of erect scales. 



42. DAHLIA. Kay In the natural tlowers neutral or in the common species more or less 



pistillate, but in the gardens most or all of the flowers are changed into rays. Inner 

 involucre of numerous more or less united scales. Akenes oblong, obscurely 2- 

 horned or notched at the apex. 



43. COREOPSIS. Eays usually 8, neutral, mostly yellow, or brown-purple at base. In- 



volucre commonly of about 8 outer loose or leaf-like scales and as many erect inner 

 ones. Chaff slender, deciduous with the flat akenes, which have mostly a pappus 

 of 2 teeth or awns, the latter not barbed downwards. 



44. BIDENS. Like Coreopsis, but several without rays, and some with slender or needle- 



shaped akenes ; all bear 2 or more rigid persistent awns, which are barbed down- 

 wards. 



45. COSMOS. DiflTers from Bidens in having the akenes distinctly beaked, and the rays 



(in ours) purple or rose-color. 

 II 11 Akenes flattened lateralb/ (if at all\ i.e., contrary to the scaler of the involucre and 

 the chaff of the receptacle, the latter usually embracing or folded round their 

 outer margin. 



o Jlays deciduous after flowering, usually ycUoir ; native. 

 X lieceptacleflat or convex. 



39. rfELIANTHUS. Eays several or many, neutral. Scales of the involucre imbricated. 



Receptacle flat or convex. Akenes flattish, but more or less 4-angled or lenticular, 

 marginless ; pappus of 2 thin chafl'y scales corresponding with the outer and inner 

 angle of the akene, and sometimes with minute Intermediate ones, all deciduous 

 from the ripe fruit. (Lessons, Fig. 381.) Leaves simple, entire or serrate ; stems 

 not winged. 



40. VERBKSINA. Rays few (in ours 1-5), pistillate. Involucre of few erect scales. Re- 



ceptacle rather flat. Akenes flat, wnged or wingless ; pappus of 2 persistent awns. 

 Leaves simjile, decurrent into wings on the stem. 



41. ACTINOMERIS. Rays neutral, few or several. Involucre of several nearly equal 



scales. Receptacle convex or conical. Akenes flat, oval, wing-margined ; pappus 



of 2 persistent smooth awns. Leaves simple, serrate, often decurrent into wings on 



the stem. ^ ^ Receptacle high and columnar. 



8S. LEPACH YS. Like Rudbeckia (next page), but akenes flattened, wing-margined on the 



inner and sometimes on the outer edge, 1-2-toothed at summit. Disk grayish. Chatt" 



.short and truncate. Leaves alternate, pinnately compound, 

 o o Rays persistent on the fruit, becoming dry and papery, broad, pistillate and 



fertile, of various colors ; cvotic. 

 34. ZINNIA. Rays several. Receptacle conical; the oblong chalf not longer than the 



velvety-tipped disk corollas. Akenes oblong or linear, flattened, or those of the ray 



8-sided ; pappus of a chaffy awn or tooth on each angle, or sometimes hardly any. 



Leaves opposite, sessile, and entire. Heads solitary, terminating the stem or 

 I I '\ Akenes not flattened, but angled or cornered. 

 (50, 51) ANTHEMIS and ACHILLEA, in which the receptacle is sometimes chaffy, m.ny be 



sought here (p. 220). 



