65a. Heads 710 mm. wide, numerous in a dense cluster 



Tansy, Tanacetum Yulgare. 

 65b. Heads 10 20 mm. wide, few, 2 10 in a loose open cluster 



Tansy, Tanacetum huronense^ 



66a. Heads 23 mm. broad (415 dm. high) 67. 

 66b. Heads 46 mm. broad (310 dm. high) 69. 



67a. Leaf-lobes narrowly linear, strictly entire 



Wormwood, Artemisia caudata. 



67b. Leaf-lobes serrate 68. 



68a. Heads in a loose spreading panicle 



Wormwood, Artemisia annua. 



68b. Heads in axillary clusters, producing a leafy spike-like 

 panicle Wormwood, Artemisia biennis. 



69a. Leaf-lobes narrowly linear 70. 



69b. Leaf-lobes oblong to obovate, not linear 71. 



70a. Shrubby; involucre pubescent 



Southernwood, Artemisia abrotanum. 

 70b. Herbaceous; involucre glabrous or rarely pubescent 



Wormwood, Artemisia canadensis. 



71a. Leaves finely gray-pubescent on both sides 



Wormwood; Artemisia absinthium. 



71b. Leaves smooth or nearly so above, densely white-woolly beneath 



Mugwort, Artemisia Yulgaris. 



72a. Heads 24 cm. broad, purple, blue, or rarely white (3 6 



dm. high; 'summer) 92. 

 72b. Heads 1 cm. wide or less 73. 



73a. Leaves densely white-woolly beneath (flowers yellowish, late 



summer) 74. 

 73b. Leaves smooth or hairy, never white-woolly 75. 



74a. Heads 68 mm. wide (48 dm. high) 



Wormwood, Artemisia stelleriana. 

 74b. Heads 34 mm. wide (510 dm. high) 



Wormwood, Artemisia ludoviciana. 



75a. Principal bracts of the involucre 5, with frequently a few much 



smaller ones 76. 

 75b. Principal bracts of the involucre numerous 77. 



76a. Heads few in small terminal clusters; foliage somewhat 



viscid-pubescent (6 15 dm. high; flowers yellow, summer) 



114a. 

 76b. Heads very numerous in flat-topped clusters; foliage never 



viscid-pubescent (1 2 m. high; flowers white, late summer) 



105c. 



