106 COMMON CANADIAN WILD PLANTS. 



27. Aster. Rays white, purple, or blue, never, yellow, but the disk 



generally yellow. Pappus of numerous fine roughish bristles, 

 (in one species double). Achenes flattish. Heads corymbed or 

 racemose. Flowering in Jate summer. 



28. Erlg'eron. Rays and disk as in Aster, but the rays very narrow, 



and usually in more than one row. Scales of the involucre in 

 one or two rows, nearly of equal length. Pappus of long 

 bristles with shorter ones intermixed. Heads corymbed or 

 solitary. Leaves generally sessile. 



* * Pappus not of hair-like bristles, but either altogether wanting or 

 consisting of a few chaffy scales or teeth, or only a minute crown. 



+- Receptacle naked. 



29. Grlnde'lin. Rays yellow, many. Disk yellow. Heads large. 



Pappus of 2 or 3 rigid awns, falling off early. Scales of the 

 involucre with spreading tips. Coarse herbs with sessile ser- 

 rate leaves. N.W. chiefly. 



30. Gutlerre'zla. Rays yellow, few. Disk-florets 3 or 4. Heads 



numerous, small, crowded. Pappus of a few short chaffy 

 scales. A low partly shrubby plant, with narrowly linear 

 entire alternate leaves. N.W. only. 



31. Hele'iilum. Rays yellow, wedge-shaped, 3-5-clef t at the summit. 



Scales of the involucre reflexed, awl-shaped. Pappus of 5-8 

 chaffy scales, 1-nerved, the nerve usually extending to a point. 

 Leaves alternate, decurrent on the angled stem. Heads corym- 

 bed, showy. 



32. Oir.v-.ji n llK-iiiimi. Rays white ; disk yellow. Disk-corollas 



with a flattened tube. Pappus none. Heads single, or 

 corymbed. Involucre broad and flat, the scales with scarious 

 margins. Receptacle flattish. 



33. ltd Us. Rays white or pink, numerous. Scales of the involucre 



in about 2 rows. Receptacle conical, naked. Low herbs with 

 solitary heads on scapes. Escaped from cultivation. 



34. Matrlca'rla. Rays white, disk yellow. Receptacle conical. 



Achenes 3-5-ribbed. Pappus a short crown or border. 



+ +- Receptacle chaffy. 



35. An'themls. Rays white. Disk yellow. Ray-florets pistillate or 



neutral. Pappus none or a minute crown. Receptacle conical 

 more or less chaffy. Herbs with strong odour, and. pinnately 

 dissected leaves. Heads terminal. 



