COMPOSITAE. 983 



of the tubular flowers undivided. Achenes obovate, compressed, not winged, 

 i-ribbed on each face. Pappus a persistent irregularly cleft crown. [Named for 

 Dr. Geo. Engelmann, botanist, of St. Louis.] A monotypic genus. 



i. Engeimanniapinnaddda T. &G. ENGELMANNIA. (I. F. f. 3874.) Stem 

 usually branched above, 3-9 dm. high. Basal leaves slender-pctioied, 1-2 dm. 

 long, their lobes lanceolate or oblong, dentate or entire, obtuse or acutish; upper 

 leaves smaller, sessile, less divided, the uppermost sometimes entire, or with a pair 

 of basal lobes; heads usually numerous, about 25 mm. broad; outer bracts of the 

 involucre somewhat in 2 series, the first linear, the second broadened at the base. 

 In dry soil, Kans. to La., Ariz, and N. Mex. May-Aug. 



54. PARTHENIUM L. 



Perennial, mostly pubescent or canescent herbs, or shrubs, with alternate leaves, 

 and small corymbose or paniculate heads of both tubular and radiate white or 

 yellow flowtrs. Involucre broadly campanulate or hemispheric, its bracts imbri- 

 cated in 2 or 3 series, obtuse, appressed, nearly equal. Receptacle convex or 

 conic, chaffy, the chaff membranous, surrounding the disk-flowers. Ray-flowers- 

 about 5, pistillate, fertile, their ligules short, broad, 2-toothed or obcordate. Disk- 

 flowers perfect, sterile, their corollas 5 -toothed, the style undivided. Anthers 

 entire at the base. Achenes compressed, keeled on the inner face, margined, 

 bearing the persistent rays on the summit. Pappus of 2-3 scales or awns. [Greek, 

 virgin.] About 10 species, natives of N. Am., Mex., the W. Ind. and northern S. 

 Am. Besides the following, some 5 others occur in the southern and southwestern 

 U. S. 



Leaf-bases not auricled. 



Stem minutely pubescent, or glabrous below ; rootstocks thickened. 



1. P. integrifolium. 

 Stem pilose or hispid ; rootstocks slender, creeping, forming runners. 



2. P. repens. 

 Upper leaves with sessile auricled bases. 3. P. auriculatum, 



1. Parthenium integrifolium L. AMERICAN FEVER-FEW. PRAIRIE DOCK. 

 (I. F. f. 3875.) Stem stout, striate, corymbosely branched above, 3-12 dm. high. 

 Rootstocks tuberous-thickened; leaves firm, ovate or ovate-oblong, acute or acu- 

 minate, crenate-dentate or somewhat lyrate at the base, hispidulous and roughish on 

 both sides, the lower and basal ones petioled, often 3dm. long and 12 cm. wide, the 

 upper 'Smaller, sessile and partly clasping; involucre nearly hemispheric, about 

 6 mm. high, its bracts firm, the outer oblong, densely appressed -pubescent, the 

 inner broader, glabrous, or ciliate on the margins; rays white or whitish. In dry 

 soil, Md. to Minn., Ga., Mo. and Tex. May-Sept. 



2. Parthenium repens Eggert. CREEPING OR HAIRY PARTHENIUM. (I. F. 

 f. 3876. ) Similar to P. integrifolium, but lower, seldom over 6 dm. high. Root- 

 stocks slender, forming runners; stem pilose or hispid with spreading hairs; leaves 

 hispid on both s'des, irregularly crenate, sometimes lyrate at the base, the teeth 

 rounded and obtuse ; heads fewer, slightly larger, in a smaller looser corymb; 

 outer bracts of the involucre proportionately broader. Mo. and Kans. April-July.' 



3. Parthenium auriculatum Britton. AURICLFD PARTHENIUM. (I.F.f. 3875^.) 

 Rootstock an oval erect tuber twice as long as thick; stem villous-pubescent, 4-7 

 dm. high. Leaves rough above, villous, especially on the veins beneath, oval, 

 ovate or oblong, irregularly crenate-dentate, some or all of them laciniate or pinnat- 

 ifid at the base, the basal and lower slender-petioled with petiole as long as the 

 blade, or longer, the upper with a sessile clasping auricled base, or with margined 

 clasping petioles ; inflorescence densely corymbose, its branches villous-tomentose; 

 bracts of the involucre densely canescent. Near Clarksville, Va.; Alleghany Mts. 



55. CRASSJftJA Scepin. [ZINNIA L.] 



Annual or perennial herbs, some species shrubby, with opposite entire, or 

 sparingly serrate, mostly narrow and sessile leaves, and large or middle sized heads 

 of both tubular and radiate flowers. Ray-flowers pistillate, yellow or variegated, 

 persistent on the achene. Disk-flowers perfect, fertile; corolla cylindraceous. its 

 lobes villous. Involucre campanulate to nearly cylindric, its bracts obtuse, dry, 



