Oedbr YC^-COMPOSIT^. 443 



6f high. Eadioal petioles If long. Iivs. 4 to 12' long, J as wide. Hda. white, 

 with 5 verj short euouUate rays. Jl. — Sept. 

 2 P. Hysteropliorus L. Annual, puberulent, decumlient, lower Ivs. lipinnatifid, 

 upper linear ; hds. numerous, yery small, in a diffuse panicle. — River banks. Ma. 

 to La. 



44. rVA, L. Maesh Elder. Highwater Shrub. Heads dis- 

 coid, monfflcious, involucre of 3 to 9 scales, distinct or partly united ; 

 marginal flowers 1 to 5, fertile, the others sterile; receptacle chafty ; 

 achenia obconic, obtuse ; pappus none.— Herbs or shrubs. Lower Ivs. 

 opposite. 



1 I. frutesoens L. Shrubby 1 Ivs. fleshy, lanceolate, coarsely serrate; upper 

 lance-linear, entire ; hds. axillary ; scales 5, distinct, rounded ; acli. 5. — Borders 

 of salt marshes^ Mass. to Ha., common. St. 3 to 8f high, with numerous op- 

 posite branches and Ivs. Hds. small, green, drooping on short stallss, in leafy, 

 paniculate racemes. Jl.^— Sept. 



2 I. ciliata "Willd. Annual, hairy; Ivs. ovate, acuminate, petiolate, coarsely 

 toothed, upper lance-ovate ; hds.spicate; scales 3, distinct, roundish, ciliate; ach. 

 3. — ^Wet grounds. 111. to La. A coarse plant of no beauty, 3 to 7f high. Lvs. 

 3 to 4' long. Spikes dense, 3 to 5' long, numerous, panicled, green, hke an 

 Ambrosia. Aug. — Oct. 



3 I. imbrioaria "Walt. Herbaceous, terete, glabrous; lvs. fleshy, linear-lanceo- 

 late, 3-nerved, tapering to the sessile base ; hds. axillary ; irwol of G to 9, fleshy; 

 obtuse, rounded scales in 2 rows, their margins scarious, lacerated ; ach. 2 to 4. — 

 li Sea coast, N. Car. to Fla. Plant 1 to 2f high. Lvs. 1 to 2' long. Hds. 

 drooping, on short pedicels, ia leafy clusters or racemes. . Jl. — Oct. 



45. AMBRO'SIA, Tourn. Horse-weed. (Gr. duPpoma, food of the 

 gods; a term strangely applied). Hds. heterocephalous. Sterile: 

 involucre of several scales united into a depressed, hemispherical cup, 

 many-flowered: anthers approximate, but distinct; receptacle naked. 

 Fertile ; involucre 1-loaved, entire or 5-toothed, 1-flowered ; corolla 

 ; styles 2 ; stamens 0. — Herb^ous plants with mostly opposite lvs. 

 and unsightly flowers. 



I sterile heads sessile, densely spieate, chaffy. Leaves altevnate No. 4 



~ ..... . . . ~ .^ — Leaves opposite X ' 



— Leaves alternate Nos, 



Sterile heads pedicellate, raccmed, not chaffy. — Leaves opposite No. 1 



alti ■ -, . - 



1 A. trifida L. Hairy, rougli; lvs. S-lobed, serrate, the lobes ovaWanceoIate, 

 acuminate ; fr. with 6 ribs ending below the conical summit. — 3) A very tall, 

 herbaceous plant, along streams, Ac. Can. and H. S., common. 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 slender, leafless, 

 terminal racemes, the fertile in axillary glomerules. Aug. — It is greedily eaten 

 by horses. 

 p. INTEGEIEOLIA. Lvs. ovate, acuminate, serrate, bristly on both sides, ciliate 

 at base, often some of them 3-Iobed'. (A. integr'ifolia Muhl.) 



2 'a. artemisifefolia L. Hos-webd. Lvs. iwice-pinnatifid, nearly smooth; peiioles 

 ciliate; rac. terminal, panicled; si. virgate. — Q 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 ter- 

 minal racemes, the fertile ones sessile about the axfla of the upper leaves. Aug., 

 Sept: (A. elatior Ph.) 



3 A. psylostaohya DO: Whitish with appressed wooUy hoArs, branched; lvs. 

 crowded,, rigid, the lower opposite, bipinnatifid, upper lanceolate, sessile, piu- 

 natifid ; sterile hds. in spioate racemes,, fertile clustered at the base of the sterile 

 spikes, in the axils of the upper leaves; fr. hairy. — (J) Prairies, Wis. to Tex. 

 Stem 1 — 5f high, at length very branching and leafy. Aug., Sept. 



