38 * ASTERACEAE 



Helichrysum — Everlasting 



(Gr. helios, sun, chrysos, gold, referring- to the golden heads of some varieties) 

 Leaves lance-oblong, entire; scales papery, yellow, white or pink //. bractedium 



Eupatorium — Eupatorium 



(Gr. eupatorion, a kind of medicinal plant) 



1. Leaves petioled 



a. Leaves in whorls of 3-6 



(1) Leaves hairy and wrinkled E. maculdtum 



(2) Leaves smooth E. purpureum: Joe-pye 



weed 



b. Leaves opposite E. ageratoides: sanicle 



2. Leaves sessile, opposite as a rule 



a. Leaves narrowed at base E. altissimum 



b. Leaves clasping, perfoliate E. perfolidtum; boneset 



Kuhnia — Knhnia 



(Named for Dr. Kuhn, a botanical collector of the 18th century) 

 Leaves lanceolate ; heads cream-colored K. eupalorioides 



Vernonia — Iron weed 



(Named for Vernon, an English botanist) 



1. Bracts with long spreading awns V. noveboracensis 



2. Bracts merely acute V. fasciculdta 



Agerat.um — Ageratum 



(Gr. ageraton, everlasting) 

 Leaves ovale or cordate; flowers blue, rarely white A. mexicdna 



Xanthium — Cocklebur 



(Gr. name of a plant yielding a yellow dye; xanthos, yellow) 

 Leaves ovate; involucre with hooked spines X. canadense 



Iva — Marsh Elder 



(Of doubtful meaning) 

 Leaves ovate, white below; involucre smooth /. xanthifolia 



Tanacetum — Tansy 



(From tansy, everlasting, from Gr. athanasia, immortality) 

 Leaves twice pinnatifid, strong-scented; flowers greenish yellow T. vulgdre 



Artemisia — Wormwood 



(From Artemisia, wife of Mausolus) 



1. Leaves entire or lobed at tip 



a. Leaves glabrous, linear A _ dracunculoides 



b. Leaves densely hairy or woolly 



(1) Leaves linear j_ glaiica 



(2) Leaves oblong to lanceolate A. gnaphalodcs 



2. Leaves divided 



a. Heads erect 



(1) Leaves typically hairy; perennial A. canadensis 



(2) Leaves glabrous; annual or biennial A. biennis 



b. Heads drooping 



(1) Leaves silvery 



(a) Leaf segments linear A. frigida 



(b) Leaf segments broad, ovoid A. absinthium 



(2) Leaves green A _ a b r 6ianum 



Ambrosia — Ragweed, Kinghead 



(Gr. name of a plant) 

 1. Leaves palmately divided; tall A trifida 



