Jones: Flora of Illinois, 152. Compositae 265 



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37. Helenium L. — Sneezeweed 



1. Leaves lanceolate to elliptical, more or less decurrent on the angular stem; 

 rays 1-2 cm. long; plants perennial. 



2. Disk yellow; leaves lanceolate or oblanceolate, mostly dentate; ray-flowers 

 fertile; low meadows, and along ditches, streams, and ponds, common. 

 [H. latifolitim Mill.; H. canaliculatum Lam.; H. altissimum Link ex 

 Rydb.} Aug.-Oct H. dutumnale L. 



2. Disk brownish-purple; leaves linear-lanceolate, mostly entire; ray-flowers 

 neutral, often brownish purple at base; roadsides, meadows, and pas- 

 tures, chiefly in the s. part of the state. [H. polyphylliim Small]. July- 

 Sept - H. nudiflorum Nutt. 



1. Leaves narrowly linear, numerous, entire, not decurrent; rays 6-10 mm. long; 

 disk yellow; plants annual; moist ground, s. 111., rare; Jackson Co., Gleas- 

 on'in 1900. Aug.-Oct H. tenuijoliutn Nutt. 



38. Dyssodia Cav. 



(Dochera Willd.) 



D. papposa (Vent.) Hitchc. Roadsides and fields. Sept. -Oct. 



Tribe 9. Anthemideae 



39. Achillea L. — Yarrow 



A. 77iillefoliU777 L. Roadsides, fields, lawns, etc., very common; nat. from 

 Eur. May-Aug. Rays sometimes pink. 



40. Anthemis L. 



1. Rays 10-18, white; achenes not flattened. 



2. Chaff of the receptacle subulate, stiff, subtending only the inner flowers; 



rays neutral; achenes sparsely glandular-tuberculate, 1-1.5 mm. long; 



plants annual, ill-scented when fresh; fields and waste places, common; 



nat. from Eur. May-Sept. \Maruta cotula (L.) DC] Dog- fennel or 



Mayweed A. cotula L. 



2. Chaff membranous or absent; rays fertile. 



3. Chaff broad, obtuse, or absent; achenes obtusely 3-angled, 1-1.5 mm. 

 long; plants perennial, tomentulose, pleasantly aromatic; cult., and 

 occasionally spont.; introd. from Eur. June -Aug. Garden Chamomile 

 A. nobilis L. 



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

 plants annual; fields and waste places, 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 perennial, pubescent; fields and 

 waste places, escaped from cult.; introd. from Eur. June-Sept. [Cota tmc- 

 toria (L.) J. Gay] A. tinctoria L. 



