125. CoMPOsiTAE 265 



3. Chaff linear-lanceolate, cuspidate; achenes 10-ribbed, 1.5-2 

 mm long; plants annual; fields and waste places, rare; nat. 



from Eur. May-Aug. Field Chamomile A. arvensis L. 



I.Rays 20-30, yellow, pistillate; achenes 4-angled and somewhat 

 compressed; chaff lanceolate, acuminate, rigid; plants peren- 

 nial, pubescent; fields and waste places; escaped from cult.; 



introd. from Eur. June-Sept. [Cota tinctoria (L.) J. Gay] 



A. tinctoria L. 



45. Matricaria L. 



1. Rays present, white; disk-corollas 5-lobed; roadsides and waste 

 places, occasional; chiefly in the southern half of 111.; nat. from 

 Eur. May-Oct. Wild Cliamomile M. chaniomilla L. 



1 . Heads discoid ; corollas 4-lobed ; roadsides, farmyards, and 

 waste places, common; nat. from the Pacific Coast. May-Aug. 

 Pineapple-weed M. matricarioides (Less.) Porter 



46. Chrysanthemum L. 

 1. Heads 3-5 cm broad, few or solitary; rays 20-30; fields, roadsides, 

 and waste places, common; nat. from Eur. May-Aug. Ox-eye 

 Daisy [Leucanthemum vulgare Lam.; C. leucanthemum var. 



pinnatifidum Lecoq. & Lamotte] C. leucanthemum L. 



1. Heads 5-15 mm broad, corymbose; rays 10-15, or absent. 



2. Leaves pinnatifid; rays 3-8 mm long; roadsides, nat. from Eur.; 



Du Page, Lake, and Peoria counties. Feverfew 



C. parthenium (L.) Bernh. 



2. Leaves crenate; rays minute or absent; waste places; escaped 



from cult.; nat. from Eur. Sept. -Oct. Costmary 



C. halsamita L. 



47. Tanacetum L. — Tansy 

 T. vulgare L. Waste places; escaped from cult.; nat. Irom Eur. 

 July-Sept. 



48. Artemisia L. — Wormwood 



1. Leaves or their divisions linear to filifonn, glabrous, or nearly so. 

 green. 

 2. Bracts of the involucre glabrous; heads 2-3 nun broad; disk- 

 flowers sterile. 

 3. Leaves simple, all entire, or the lower trifid ; plants perennial; 



prairie soil, rare. July-Sept. [A. cernua Nutt.] 



A. dracunculoides Pursh 



3. Leaves 1- to 3-pinnately divided; plants biennial; sandy 



soil, local. July-Sept A. caudata Michx. 



2. Bracts tomentulose; heads 3-4 mm broad; disk-flowers fertile; 

 leaves 1- to 3-pinnately parted; plants perennial, shrubby; 

 often cultivated, and sometimes persisting; introd. from Eur. 



Aug.-Sept. Southernwood A. abrotanum L. 



1. Leaves or their divisions lanceolate to linear. 



