444 ORDER 70. COMPOSITE. 



4 A. bidentata MX. Very hirsute ; st. branching ; branches simple ; Ivs. crowded, 

 mostly alternate, closely sessile or partly clasping, undivided, oblong, with a single 

 tooth or short lobe on each side near the base ; sterile hds. densely spicate, fer- 

 tile axillary ; fr. -angkd, acutely pointed, the 4 ribs produced in 4 short spines. 

 (T) Prairies, 111. to La, Stem 1 3f high, with numerous leaves and very dense, 

 terminal spikes. Jl. Sept. 



46. XAFTTHIUM, Tourn. CLOT-WEED. Heads heterocephaloua. 

 Sterile, in globous heads ; scales distinct", in one row ; anthers approxi- 

 mate, but distinct ; receptacle chaffy. Fertile : involucre 2-leaved, 

 clothed with hooked prickles, 1 or 2-beaked, enclosing 2 flowers ; 

 stamens 0. (T) Coarse weeds with alternate Ivs. 



1 X. Strumarium L. Rough, unarmed, branching; Ivs. cordate, lobed, 3-veined, 

 unequally serrate ; fr. elliptical, armed with uncinate, stiff thorns, and ending 

 with 2, spreading, straight horns. A coarss, rough plant, in old fields, &c., N. 

 Eng. and Mid. States. Stem branched, bristly, spotted, 2 3f high. Leaves 

 large, on long stalks, rigid. $ Fls. few together, terminal, globular, green ; $ 

 in sessile, axillary tufts. Fruit a hard, 2-celled burr, near an inch long, covered 

 with stiff, hooked prickles, winch, like those of the common burdock, serve to 

 disperse the seeds. Aug. Variable; fruit more than 1', or less than 1' in length ; 

 thorns very close or somewhat scattered ; horns spreading or incurved. (X. 

 echinatum Murray.) 



2 X. spinosum L. Wfiitish-downy, armed with triple, slender, subaxillary spines, 

 spines at base of the leaves triple, slender ; Ivs. ovate-lanceolate, cuneate at base, 

 petiolate, 3-lobed or dentate or entire, under surface and veins above whitish, 

 twico longer than the spines ; invol. oblong, with slender, uncinate thorns. 

 Roadsides and fields, Mass, to Penn. and Ga. Plant about If high, very con- 

 spicuously armed with straw-colored spines f 1' long. Heads sessile, sterile in 

 the upper, fertile in the lower axils. Sept. Nov. 



47. MEL ANTHER A, Cass. (Gr. fiekag, black, Lat. anthera, an- 

 ther.) Heads discoid ; flowers all tubular, ; scales in 2 subequal 

 scries ; receptacle chaffy, the pales partly investing the flowers ; 

 achenia short, truncate, angular ; pappus a few minute caducous awns 

 or bristles. 2 Herbs rough, with square stems, opposite, petioled, 3- 

 veined Ivs. and long peduncled hds. Cor. white. Anth. black, tip- 

 ped with a white appendage. 



M. hast at a MX. Lvs. hastately 3-lobed, acuminate, dentate, on slender petioles ; 

 scales ovate-lanceolate, acuminate, pales rigid, cusp-pointed. Dry soils, S. Car 

 to Fla and La. Sts. 3 to Gf high, beautifully variegated with purple, the branches 

 slender, erect, few-flowered. Lvs. deep green, very rough, 4 to 6' long, the 

 upper smaller. Hds. near G" broad, of stiff scales and singularly contrasted, 

 colors. Jl. Sept 



48. ZIN'NIA, L. (To John Godfrey Zinn, a German botanist, 

 1557.) Heads radiate ; rays ?, disk tubular, $ ; scales of the involucre 

 oval, margined, imbricate ; receptacle chaffy, conical ; pappus of the 

 disk of 1 or 2 erect, flat awns. (I) American herbs, with apposite, 

 entire Ivs. and solitary terminal hds. Rays bright colored, showy. 



Z. nrultiflora L. Lvs. ovate-lanceolate, abrupt at base, scarcely petioled; hds. 

 on peduncles as long as the Ivs. ; pales obtuse, entire ; ach. of the disk with one 

 awn . Fields and waysides, Ga., Fla., to Tex. Sts. 6' to 2f high, simple or 

 nearly so. Lvs. 1 to 2' long, rather obtuse. Ped. enlarged upwards, hollow 

 Rays about 12, oval, scarlet within, yellowish without. May, Jn. 



2 Z. elegaiis L. Lvs. ovate, cordate, sessile-amplexicaul ; hds. on ped. 

 longer than the Ivs. ; pales serrated; ach. of the disk with 2 awns. Gardens; 

 Plant tall, elegant and showy, with brilliant fls. of varying colors, as orange, 

 scarlet, crimson, purple, violet and white. Jl., Aug. f Mexico. 



