184 COMPOSITE FAMILY. 



*-*. ++ ++ -M- -n- ^4)fcenf incurved or boat-shaped, rough-tub ercled on the back : no pap- 



pus: rays numerous in more than one row : flowers nil yellow or orange, 

 18. CALENDULA. Heads showy, solitary terminating the branches, with the very 

 numerous rays pistillate and fertile, expanding in sunshine or bright daylight : 

 the disk-flowers sometimes lew in the eentre and sterile. Involucre of nu- 

 merous short green scales. Receptacle flat. Akenes all that mature belong- 

 ing to the ray-flowers, strongly incurved, some of them even horse-shoe- 

 shapcd, or coiled into a ring, and (especially the outer ones) with thickened 

 margins. 



H- +- A chaff on the receptacle behind each flower. 



*-+ Only the ray-flowers fertile or MflterMM their akenes ; tliose of the disk, even if 

 appart ntty perfect, always sterile : flowers all yellow. Coarse tall herbs. 



49. POLYMNI A. Heads rather small or middle-sized, with about 5 leaf-like scales 



to the involucre, and some thin and small inner ones, few or several ray- 

 flowers producing turgid obovate or partly triangular akenes with no pappus. 

 Herbage clammy-pubescent and rather 'strong-scented: all but the upper- 

 most leaves opposite, and their petioles winged or dilated and stipule-like at 

 the clasping base. 



50. SILPHIUM. Heads mostly large, with numerous somewhat leafy-tipped or 



green scales to the involucre imbricated in 2 or more rows, numerous ray- 

 flowers producing very broad and flat akenes (parallel with the scales of the 

 involucre), which have commonly a wing-like margin and 2 teeth or a notch 

 at the top. Juice resinous. 

 -w- Disk-flowers perfect and fertile, those of the ray pistillate and fertile or neutral. 



a. Akenes flattened pnrdllt I with ihe scidts of the involucre rind cluijf of the recep- 



tacle, or in 53 sometimes very lender. Leaves yenerally opposite : involucre 

 double, the outer mostly leaf-like, the inner of erect scales. 



51. DAHLIA. Rays in the natural flowers neutral or in the common species more 



or less pistillate, but in the gardens most or nil 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. 



52. COREOPSIS. Rays usually 8, neutral, mostly yellow, or brown-purple at base. 



Involucre 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 

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



63. 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 downwaids! 



b. Akenes flattened if at all contrary to the scales <f the involucre and the chaff of 



the receptacle, having the latter usually embracing or folded round their outer 

 margin. 



= Rayt deciduous after flowering, yellow, sometimes brown-purple at base in 60, 61, 

 or white in one o/'55. Leaves either opposite or alternate in s'ime genus, in 

 54 - 5t>. 



64. AC TINOMERIS. Rays neutral, few or several. Involucre of several nearly 



equal scales. Receptacle convex or conical. Akenes flat, oval, wing-mar- 

 gined: pappus of 2 persistent smooth awns. Leaves simple, serrate, often 

 decurrent into wings on the stem. 



66. VERBESINA. Rays few (in ours 1-5), pistillate. Involucre of few erect 

 Smiles. Receptacle! rather flat. Akenes flat, winged or wingless : pappus of 

 2 persistent awns. LeftVM simple, decurrent into wings on the stein. 



53. XIMENESIA. Rays numerous, pistillate. Scales of the involucre spreading. 



R -ptacie fl.irtish or convex. Akenes of the ray wrinkled and wingless; 



those of the disk flat and wing-margined, with two slender awns united to 

 the wing. Leaves mostly with winged petioles which are dilated and clasp- 

 ing at the lia e. 



57. 1IKL1ANTHUS. Rays several or many, neutral. Scales of the involucre im- 

 bricated. Receptacle flat or convex. Akenes flatfish, more or less 4-angled 

 or lenticular, marginless: pappus of 2 thin chall'y scales corresponding with 

 the outer and inner angle of the akene, and sometimes with minute inter- 

 mediate one-, all deciduous from the ripe fruit. (Lessons, p. 130, fig. 293.) 

 Leaves simple, entire or serrate: stems not winged. 



08. IIKLIOI'SIS. Rays K> or more, pistillate. Scales of the involucre in 2 or 3 

 rows, the inner shorter than the disk. Receptacle conical. Akenes 4-angled, 

 somewhat cubical: no pappus. Leaves opposite, petioled, triple-ribbed. 



