182 KEY AND FLORA 



XXXI. AN'THEMIS, Dog Fennel 



Herbs with pinnately dissected leaves and numerous heads, 

 terminating the branchlets. Scales of the involucre in several 

 series, one above the other. Eeceptacle convex or conical, 

 having chaffy scales among the flowers. Ray flowers white, 

 those of the disk yellow. Pappus none. Akenes ribbed. 



A. Cot'ula L. Whiteweed, Mayweed. This is a common intro- 

 duced weed, and blooms in summer and fall. It has a strong, acrid 

 taste disagreeable to animals. 



XXXn. ACHILLE'A, Yarrow, Milfoil 



Perennial herbs, strong-scented, with pinnately dissected 

 leaves. Stems usually simple, terminated by dense corymbs of 

 small heads of tvhite or innkish flowers. Involucres with 

 small scales in several rows. Pappus none, akenes flattened, 

 margined. Bracts of the receptacle thin and transparent. 



A. millefolium L. This is common and widely distributed. The 

 leaves are disposed to form rosettes at the base of the stem, and are 

 delicate and fern-like. 



XXXIII. MATRICA'RIA, Chamomile 



Erect simple or branching herbs, with pinnately dissected 

 leaves. Heads terminating the branches, on short peduncles. 

 Bracts of the involucre in several series. Disk greenish 

 yelloio, conical. Rays white when present. Pappus in a crown 

 or wanting. 



M. discoi'dea DC. Manzaxilla. Annual, erect, branching. 

 Heads with a high conical disk and no rays. Involucre with white, 

 papery margins to the broadly ovate scales. Akenes with a crown- 

 like margin in place of pappus. This plant has the odor of ripe 

 apples. Widely distributed. 



XXXrV. ARTEMISIA, Wormwood, Sagebrush 



Herbs or shrubs with bitter taste and alternate leaves. 

 Heads greenish, small, tvithout rays, numerous in racemes or 

 panicles. Scales of the involucre dry, with papery margins. 



