DICOTYLEDONS. 245 



pistillate and fertile, or neutral, the rays euneate, 3-o-lobed, 

 disk flowers perfect, tubular, 4-o-lobed ; achenes top-shaped, 

 hairy, ribbed ; pappus of 4-5 entire, toothed or awned scales. 



1. H. NUDIFLORUM Xutt. SxEKZEWKKi). Perennial : steiu sleii- 

 der, erect, pubescent, branched above, 1-2 ft. high; leaves lanceo- 

 late, entire or slightly toothed, the lower petioled, the upper sessile; 

 heads numerous, ray flowers 10-1."), neutral, yellow or yellow and 

 brown, disk flowers [)urple : achenes hairy on the ribs; pappus of 

 ovate, denticulate, awned scales. ]\lay-fliiut'. Common on river 

 banks. 



2. II. TENLiFOLiUM Xutt. 1)11 TKi! w KKD. Anuual ; steuierect, 

 widely branched, smooth, 1-2 ft. high; leaves very numerous, fili- 

 form, sessile ; heads on long and slender i)eduncles; bracts subulate, 

 soon reflexed ; ray flowers 4-8, fertile, the rays droo])ing; pappus of 

 ovate, entire, awned scales. June-October. .V troublesome road- 

 side and pastiu-e weed. 



XIV. ACHILLEA. 



Perennial ; leaves alternate, pinnately divided ; heads radi- 

 ate in a terminal corymb ; involucral bracts imbricated in sev- 

 eral series, the outer shorter ; receptacle chaffy ; ray flowers 

 wliite or pink, pistillate and fertile, disk flowers perfect, 

 tubular, 5-lobed ; achenes oblong, compressed, slightly mar- 

 gined ; pa])i)us none. 



A. Mii.i.Kroi.nM L. Y\i;i;(t\\. Siems often clustered, erect 

 from a creeping rootstock. simple juibescent or tomentose. l-*J ft. 

 high; leaves lanceolate or ohlong, the segments finely cut and 

 divid<'d, smooth or jiubescent, the lower ])etioled, tht^ upjier sessile; 

 heads small, numerous, in flat-topi)ed corynd)s; bracts ])ubescent; 

 ray flowers 4-5, white or ]unk, rays :]-lobed at -the ajK-x. May- 

 September. Common in old fields. 



XV. SENECIO. 



Annual or ix-rennial ; stems often hollow; leaves alteriuite, 

 entire or i)innately divided ; heads radiate or discoid, in 

 terminal corymbs ; bracts mostly in a single row, often witli a 

 few shorter ones at the base : re(;eptacle naked or pitted : ray 

 flowers yellow or orange, j)istilhite and fertile when present, 

 disk flowers tubular, i)erf('ct; acdienes terete or compressed, 



