COMPOSITAE. 263 



segments once or twice pinnately-cleft or parted into linear acute lobes; 

 heads small, numerous, in convex or flat-topped terminal corymbs; involucre 

 ovoid or subglobose, 3-5 mm. high; rays 4 or 5, white, 2-4 mm. long. Abun- 

 dant everywhere. 



394. ANTHEMIS. 



Herbs; leaves alternate, mostly tripinnately divided; heads 

 many-flowered; ray-flowers numerous, commonly conspicuous, 

 pistillate or sometimes sterile; disk-flowers fertile; involucre 

 broad, the scales very numerous, imbricated and appressed; 

 receptacle convex to oblong-conical, chaffy, with slender or thin 

 scales or awns, subtending at least the central flowers; pappus 

 none, or a short chaffy crown; akenes obovoid or oblong, 4- or 5- 

 angled, 8-10-ribbed or many-striate, truncate at the apex. 



Leaves glabrous, ill-scented ; rays neutral. A . cotula. 



Leaves pubescent, not ill-scented; rays fertile. A. arvensis. 



Anthemis cotula L. Dog Fennel. May-weed. Annual, much branched, 

 puberulent or glabrate, 30-60 cm. high; leaves 1-3 times pinnately-dissected 

 into thread-like lobes; heads 2 cm. broad; receptacle conical, with bristly 

 bracts near the apex, none at the margin; involucral bracts oblong, obtuse, 

 pubescent; rays white, 10-18, becoming reflexed in age; akenes 10-ribbed, 

 roughened; pappus none. A weed, becoming common; the herbage strong 

 scented. 



Anthemis aivensis L. Corn Chamomile. Pubescent annual herb re- 

 sembling A. cotula but not ill-scented; leaves less finely 1-2-pinnately parted; 

 chaff lanceolate, pointed, subtending and exceeding all the disk-flowers; 

 akenes smooth; pappus a minute jjorder. Sparingly introduced. 



395. MADIA. Tarweed. 



Annuals; leaves linear or lanceolate, entire or slightly toothed, 

 at least the upper alternate; heads peduncled, clustered; flowers 

 yellow; ray-flowers 1-20 and pistillate, or rarely wanting; disk- 

 flowers 1-5, perfect; receptacle chaffy only at the margin; 

 pappus none or of several small scales in the sterile flowers ; ray- 

 akenes laterally compressed, enclosed in the infolded involucral- 

 scales; disk-akenes laterally compressed. 



Heads small, long-peduncled; disk flower solitary. M. exigua. 

 Heads larger, sessile or short-peduncled; disk flowers several. 



Involucres laterally compressed; heads densely glomerate. M. glomerata. 

 Involucres campanulate; heads loose or scattered. 



Akenes of the rays broad ; herbage lemon-scented. M. citriodora. 



Akenes of the rays compressed; herbage heavy-scented. M. racemosa. 



Madia exigua (Smith) Greene. Stems slender, erect, usually branched 

 above, hirsute-pubescent below, glandular above, 10-30 cm. high; leaves linear, 

 1-3 cm. long; heads 2-3 mm. high, long-peduncled, loosely corymbed; bracts of 

 the involucre 4-8, enclosing as many ray-flowers which scarcely exceed the 

 bracts; disk-flowers solitary; akenes black, obovate, but lop-sided, that of the 

 disk-flower straight, those of the ray-flowers curved. Dry ground, rather 

 common. 



