226 COMPOSITE FAMILY. 



18. BOLTONIA. Flowers resembling those of Aster and Erigeron. Receptacle conical or 

 hemispherical. Akenes very flat, obovate or obcordate with a callous margin or 

 wing ; pappus of several minute and short bristles, and commonly 2 or 3 short awns 

 Leafy-stemmed, tall, branching kerbs, with pale-green thickish and chiefly entire 

 leaves often turned edgewise. 



51. ACHILLEA. Heads mostly with few and white (rarely rose-red or yellow) rays. 



Keceptacle small, flattish, chaffy. Akenes oblong, margined ; no pappus. 



= = Akenes incurved or boat-shaped, rough-tubercled on the back ; no pappus ; rays 

 numerous in more than one row ; flowers all yellow or orange. 



62. 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 few in the center and sterile. Involucre of numerous short 

 green scales. Receptacle flat. Akenes (all that mature) belonging to the ray flowers, 

 strongly incurved, some of them even horseshoe-shaped, or coiled into a ring, and 

 (especially the outer ones) with thickened margins. 



= = = Akenes not flat, nor boat-shaped ; rays pistillate and fertile except sometimes 

 in Anthemis and Gaillardia, often yellow. 



1 Pappus a short crown, or none. 



50. ANTHEMIS. Rays pistillate and fertile (or neutral in one), numerous, white or some' 

 times yellow. Involucre of many small, close-pressed scales. Receptacle convex, 

 with some slender chaff, at least at the center. Akenes terete, mostly ribbed. 

 Leaves once to thrice pinnately divided. 



52. CHRYSANTHEMUM. Rays pistillate and fertile, numerous. Receptacle convex or 



flat, without chaff, except in some double-flowered varieties. Disk flowers mostly 

 with a flattened tube. Pappus none. Otherwise nearly as in Anthemis. 



B II Pappus of 5-10 conspicuous thin chaffy scales with midrib more or less extended 

 into a bristle or awn, or of a few rigid, caducous awns ; rays not very numer- 

 ous, yellow or partly reddish or broionish-purple, never white. 



9. GRINDELIA. Heads large and many-flowered, rarely rayless. Scales of the invo- 

 lucre in several rows or series, the tips green and more or less spreading, often 

 resinous. Akenes short and thick, truncate, glabrous. Pappus of a few rigid awns, 

 caducous. Leaves alternate. 



46. HELENIUM. Rays pistillate. Involucre of a few small and narrow spreading or 



reflexed scales. Receptacle globular or conical. Heads mostly corymbed. Akene 

 top-shaped and ribbed. Pappus of 5-8, 1-nerved and thin chaffy scales. (Lessons, 

 Fig. 382.) 



47. GAILLARDIA. Rays often neutral, often party-colored. Involucre of two or more rows 



of loose, leafy -tipped scales. Receptacle convex. Disk flowers often purple ; the styles 

 with very slender hispid branches. Heads solitary on slender terminal peduncles. 

 Akene top-shaped and 5-ribbed, villous. Pappus of 5-10 long and thin scales. 



H--H- Chaff on the receptacle, one bract behind each flower in the head. 



Disk flowers, even if apparently perfect, always sterile, only the ray flowers fertile 

 or maturing their akenes ; flowers all yellow. Coarse tall herbs. 



I Flowers yellow or yellowish. 



28. POLYMNIA. 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-pubes- 

 cent and rather strong-scented ; all but the uppermost leaves opposite, and their 

 petioles winged or dilated and stipule-like at the clasping base. 



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



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

 ing 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. 



