CALENDULA. LXXV. COMPOSITE. 353 



59. AMBROSIA. 



Gr. a/x/?(joo-ta, food of the gods ; a term strangely apjl'cd. 



Heads heterocephalous. Sterile. Involucre of several united 

 scales, hemispherical, many-flowered ; anthers approximate, but dis- 

 tinct ; receptacle naked. Fertile. Involucre 1 -leaved, entire or 5- 

 toothed, 1 -flowered, corolla 0; styles 2; stamens 0. Herbaceous 

 plants with mostly opposite Ivs. and unsightly flowers. 



1. A. TRIFIDA. Tall Ambrosia. 



Hairy, rough ; Ivs. three-lobed, serrate, the lobes oval-lanceolote, acumi- 

 nate ; fr. with 6 lines below the summit. (J) A very tall, herbaceous plant, not 

 very common in N. Eng., found in hedges and low grounds in the valley of 

 Connecticut river. In the W. States it is abundant! Stem 5 lOf high, erect, 

 branching, furrowed. Leaves opposite, in 3 large, deep lobes with long points 

 and close serratures. Flowers mean and obscure, in long, leafless spikes, axil- 

 lary and terminal. Aug. 



/?. inlcgrifolia. T. & G. (A. integrifolia. Mukl.) Lvs. ovate, acuminate, 

 serrate, bristly on both sides ; ciliate at base, often some of them 3-lobed ; rac. 

 terminal, single or ternate. 



2. A. ARTEMisijEFOLiA. (A. elatior. Ph.} Hog-weed. 



las. twice-pmnatifid, nearly smooth ; petioles ciliate ; rac. terminal, pani- 

 cled; st. virgate. A common and troublesome weed of the' gardens, fields, 

 &c. (Can. to Ga.) far more worthy of its English than its Latin name. Stem 

 2 3f high, branching, pubescent when young. Leaves with segments acute 

 and parallel. Barren flowers, small, green, in terminal racemes, the fertile 

 ones sessile about the axils of the upuer leaves. Aug. Sept. 



3. CORONOPIFOLIA. Torr. & Gray. 



Canescent-strigose, branched ; Ivs. crowded, rigid, the lower opposite, bi- 



pinnatifid, upper lanceolate, sessile, pinnatind ; sterile hds. spicate, yer^Te clus- 



" tered at the base of the sterile spikes, in the axils of the upper leaves; fr. hairy. 



Prairies, Wis. to Tex. Stem 1 5f high, at length very branching and 



leafy. Aug. Sept. 



4. A. BIDENTATA. Michx. 



Very hirsute ; st. branching ; branches simple ; Ivs. crowded, mostly alter- 

 nate, closely sessile or partly clasping, undivided, oblong, with a single tooth 

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

 lary ; fr. 4-angled, acutely pointed, the 4 ribs produced in 4 short spines. 

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

 terminal spikes. Jl. Sept. 



60. I V A . 



A name of barbarous origin. 



Heads discoid ; involucre 3-leaved ; marginal flowers 5, fertile, the 

 others sterile ; receptacle hairy ; acfrenia obconic, obtuse ; pappus 0. 

 Herbs or shrubs. Lower Ivs. opposite. 



I. PRUTESCENS. High-water Shrub. Marsh Elder. 



St. shrubby ; Ivs. lanceolate, punctate, deeply serrate, rough. Qj. In the 

 borders of salt marshes, Mass, to La., common. Stem thick, 3 8f high, with 

 numerous opposite branches. Leaves numerous, 3-veined, upper ones entire. 

 Flowers green, small, drooping, in close, leafy clusters. Aug. 



TRIBE 5. CYNARE.E. 



Heads ovoid, discoid, rarely radiate, homogamous (rarely riicEcious), or hete 

 "ogamous with the marginal flowers in a single series. Style in the perfect 

 flowers often tumid near the summit. 



61. CALENDULA. 



Lat. calcnda, the first day of the month ; some species blossom monthly. 



Heads radiate involucre of many equal leaves, in about 2 series ; 



