COMPOSITyK. (COMPOSITF, FAMILY.) 217 



23. PLtrCHEA, Cass. Marsh-Fleabane. 



Heads ma)iy-fluwerc(l ; the flowers all tubular; the central perfect, but sterile, 

 few, with n .5-clert corolla; nil the others with a thread-shaped truncate corolla, 

 pistillate and fertile. Involucre imbricated. Anthers with tails. Achcnia 

 grooved. Pappus capillary, in a single row. — Herbs, somcwiiat glandular, 

 emitting a strong or camphoric odor, the heads in close compound corymbs. 

 Flowers j)urpli>li, in suinuier. (Dedicated to the Abbe Piurlie.) 



1. P. camphor^ta, DC (Salt-marsh Fleabane.) Annuul, miimUh/ 

 ri.irid, pale {l°-'2° hi.uh); haves scarcely pctiolnl, ohlow^-ovixtii or lanceolate, 

 thickish, obscurely veiny, serrate; corymb flat; involucre viscid-downy. (Co- 

 n\za camphorata, Bi(/i:l. C. Marylandica, Ptira/i.) — Salt marshes, Massa- 

 chusetts to Virginia and southward. 



2. P. foetida, DC. Pe.rcmilal, almost smooth (-2°- 4° \u'j:h); leaves disdnctli/ 

 jietioted, veiny, oval-litneeolate, poitittd at Initli tt>ds, serrate ; corymbs panieled ; 

 involucre smooth. River-banks, Ohio to Illinois, and southward. 



3. P. bifrons, DC. Perennial; leaves closely sessile or hulf-claspinfj b}- a 

 somewhat heart-shaped base, lance-oblong, sharply denticulate, veiny (only 2'- 

 3' long) ; heads clustered in a corymb ; involucre smooth. — Salisbury, ilary- 

 land ( W. M. Canby), and southward. 



24. BACCHARIS, L. GnorNnsnL-TnEE. 



Heads many-flowered ; the flowers all tubular, dicecions, viz. the pistillate and 

 staminate flowers in sejjarate heads borne by difl'erent plants. Involucre imbri- 

 cated. Corolla of the pistillate flowers very slender and thread-like ; of the 

 staminate, larger and 5-lobed. Anthers tailless. Aeheni.i ribbed. I'apjius of 

 slender capillary bristles, in the sterile j)lant scanty and tortuous; in the fertile 

 plant very long and copious. — Shrubs, commonly smooth and n\sinous or glu- 

 tinous. Flowers whitish or yellow, autumnal. (The name of some shrub 

 anciently dedicated to Bdrrlms.) 



1. B. halimif61ia, L. Smooth and soniewlmt scurfy ; branches angled ; 

 leaves obovate and wedge-form, coarsely toothed, or the upper entire ; heads 

 scattered or in leafy panicles; scales of the involucre acutish. — Sea beach, 

 Massachusetts to Virginia, and southward. — Shrub 6° -12° high; the fertile 

 plant c()ns])icuous in autinnn by its very long and white ])ap|)us. 



2. B. glomerulifl6ra, I'ers. Leaves sinituiate-oblong ; heads larger, 

 sessile in the axils or in clusters ; scales of the bell-shaped involucre broader, 

 very obtuse : otherwise like the last. — Pine barrens, E. Virginia and south- 

 ward. 



25. POLYMNIA, L. Leai -Ci r. 



Heads manyflowcrcd. radiate: tlic rays several (rarely abortive), jiisfillatc ; 

 the disk-flowers perfect but sterile. Scales of the involucre ill two rows ; the 

 outer about 5, leaf-like, large and spreading ; the inner small and membrana- 

 ceous, partly embracing the thick triangular-obovoid achcnia. l\ecej)tacle flat, 

 with a membranaceous cliaft' to each flower. Pappus none. — Tall branching 



