452 COMPOSITE. 



Hints of the tiieiiera. 



Heads scattered or solitary, terminating leafy branches or peduncles; 

 Leaves finely dissected; 



Kays 0; heads ovoid, .-.-..._-- 88 



Rays present; heads hemispherical, -.-..-- 94 



" " ; disk convex, --------- 87 



Leaves merely toothed or lobed; 



Heads rayless, ---------.--94 



" radiate; involucre hemispherical, ------ 89 



Heads sessile in the forks, rayless, ---------- .93 



Heads cymose-corynibose; 



Heads small; flowers white, --------- 90 



larger; " yellow, --.---.--91 

 Heads panicled, small, rayless, usually nodding, ------- 92 



87, CHAMiEMELUM, Toumefort. Herbs with piunately dissected 

 leaves, and rather large heads on peduncles terminating leafy branches. 

 Involucre hemispherical. Ray-flowers white; disk-flowers yellow. Chaff 

 of receptacle bristly. Achenes not flattened, glabrous; the truncate 

 summit with or without a short coroniform pappus. 



1. C. COTULA, Allioni, Fl. Pedem. i. 186 (1785); Linn. Sp. PI. ii. 894 

 (1753), under Anthemis. (Mayweed.) Strong-scented annual weed 1—2 

 ft. high, somewhat freely branching: receptacle conical, destitute of 

 chaff near the margin: achenes 10-ribbed, rugose or tuberculate. — In 

 waste grounds. July — Oct. 



88. MATRICARIA, Toumefort. Our species annual herbs, with 

 finely dissected sweet-scented foliage and rayless heads of green flowers 

 terminating the branches. Receptacle conical or ovoid, naked. Achenes 

 glabrous, 3 — 5-nerved on the sides, rounded on the back, nearly desti- 

 tute of pappus. 



1. M. discoidea, DO. Prodr. vi. 50 (1837). Tanacelum suaveolens, 

 Hook. FI. i. 327, t. 110 (1833). Low often diffusely branching, mostly 

 less than 1 ft. high, sweet-scented: heads short-peduncled: bracts of 

 involucre broadly oval, scarious, with green ceutre, not half the length 

 of the ovoid disk: achenes oblong, somewhat angled, with an obscure 

 coroniform margin at summit. — By waysides everywhere, mostly in hard 

 sterile soil. April, May. 



2. M. occidentalis, Greene, Bull. Calif. Acad. ii. 1.50 (1886). Erect, 

 very stout, l^a— 2I3 ft. high, corymbosely branched at summit, the herb- 

 age nearly scentless: heads more than twice as large as in the last and 

 6 --8 lines high: receptacle somewhat fusiform: achenes sharply angled 

 and with a broad coroniform margin below the summit. — Grain fields 



