DICOTYLEDONS. 239 



cated in several rows ; receptacle pitted ; flowers yellow, ray 

 flowers 1-16, in a single row, pistillate, disk flowers mostly 

 perfect ; achenes terete, ribbed ; pappus of numerous, slen- 

 der, scabrous bristles. A large genus, nearly all flowering 

 late in the season. 



1. S. c^siA L. Blue-stemmed Golden-rod. Stem erect, 

 slender, smootli and glaucous, usuaUy blue or purple, simple or 

 branched, 2-3 ft. high ; leaves lanceolate, acuminate, sessile, sharply 

 serrate, smooth ; heads in axillary racemes shorter than the leaves, 

 about 10-flowered; rays 3-4; achenes pubescent. August^Septem- 

 ber. In woods and thickets. 



2. S. Canadensis L. Canadian Golden-rod. Stem stout, 

 erect, rough-pubescent, branched above, 3-8 ft. high ; leaves lanceo- 

 late, serrate, 3-nerved, the lower petioled, the upper sessile; heads 

 very numerous, on one side of the curved branches of a large pani- 

 cle; involucral bracts linear; ray flowers 9-15; achenes pubescent. 

 July-Xovember. ^Margins of fields, on diy ground. 



3. S. NEMORALis Ait. FiELi) (ioLi)EN-ROD. Stciu slendcr, erect, 

 gray with dense pubescence, simple, 1-2 ft. high; leaves obscurely 

 3-nerved, the lower lanceolate to spatulate, serrate, petioled, the 

 upper lanceolate, mostly eutire, sessile ; heads many, the racemes in 

 a dense panicle with curved branches, 10-12-flowered; bracts linear- 

 oblong; ray flowers G-7 ; achenes pubescent. June-August. Com- 

 mon in open fields. 



VI. ASTER. 



Perennial or rarely annual ; leaves alternate ; heads usually 

 corymbed or panicled, many-flowered, radiate ; bracts imbri- 

 cated in several rows, the outer shorter, the ti[)S spreading; 

 receptacle naked, pitted ; ray flowers pistillate, in a single row, 

 disk flowers })erfect, tubular ; achenes compressed, nerved ; 

 pappus a single or double row of slender, scabrous bristles. 



1. A. AzriJEi's Lindl. Hlue Aster. Stem erect, slender, rigid, 

 rough, branched above, 2-3 ft. high; lower leaves lanceolate to cor- 

 date, acute or obtuse at the ajx^x, truncate or cordate at the base, 

 <Mitire, long-])eti<)l<Ml, th«; uj^ju'r lanceolate to linear, sessile, those of 

 the branch«'s subulati*; iicads numerous; involucre turbinate, the 

 hracts smooth, appressed; ray flowers 10-20, briglit Mu.-; pai.i)us 

 tawny. .luly-Septemher. On dry ground. 



2. A. rxDiLATrs L. W avv-lkaved Astkk. Stem <'re(t, rigid, 

 rough-] (ubescent, witlely branched above, 2-3 ft. higli ; leaves lanceo- 

 late to ovate, rough, eiitin*, undulate or serrate, the lower cordate, 



