Obdeb TO.— COMPOSITE. 443 



6f high. Radical petioles If long. Lvs. 4 to 12' long, £ as wide Hd3. white, 

 with 5 very short eucullato rays. JI. — Sept. 

 2 P. Hy3terophorus L. Annual, puberulent, dzcumbent, lower lvs. bipinnatifid, 

 upper linear ; lids, numerous, very small, in a diffuse panicle. — River bank.3, Fla. 

 to La. 



44. TVA, L. Marsh Elder. Higiiwater Shrub. Heads dis- 

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

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

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

 opposite. 



1 I. frutescens L. Shrubby; lvs. fleshy, lanceolate, coarsely serrate; upper 

 lance-linear, entiro ; hds. axillary; scales 5, distinct, rounded ; ach. 5. — Borders 

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

 posite branches and lvs. lids, small, green, drooping on short stalks, in leafy, 

 paniculate racemes. Jl. — Sept. 



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

 tootVed, upper lauce-ovato ; hds. spicale ; scales 3, distinct, roundish, citiaie; ach. 

 3. — Wet grounds, 111. to La. A coarse plant of no beauty, 3 to If high. Lv3. 

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

 Ambrosia. Aug. — Oct, 



8 I. imbricaria Walt. Herbaceoics, terete, glabrous; lvs. fleshy, linear-lanceo- 

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

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

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

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



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

 gods; a term strangely applied). lids, heterocephalous. Sterile: 

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

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

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

 0; styles 2 ; stamens 0. — Herbaceous plants with mostly opposite lvs. 

 and unsightly flowers. 



8 Sterile heads sessile, densely splcate, chaffy. Leaves alternate No. 4 



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



— Leaves alternate Nos. 2, <1 



1 A. trfficla L Hairy, rough ; lvs. Z-lobed, serrate, the lobes oval-lanceolate, 

 acuminate ; fr. with G ribs ending below the conical summit. — CD A very tall, 

 herbaceous plant, along streams, &c. Can. and U. S., common. Stem 5 — lOf 

 high, erect, branching, farrowed. Leaves opposite, in 3 large, deep lobes, with 

 long points and close serrature3. Flowers mean and obscure, in slender, leafless, 

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

 by horses. 



/?. integrifolia. Lvs. ovate, acuminate, serrate, bristly on both sides, ciliato 

 at base, often some of them 3-lobed. (A. integriiblia Muhl.) 



2 A. artemisiaefdlia L. Hog-weed. Lvs. twice-pinnatifid, nearly smooth ; petioles 

 ciliate; rac. terminal, panicled; st. virgate. — 1) A common and troublesome 

 weed of tho gardens, holds, &e. (Can. to Ca.) far more worthy of its English 

 than its Latin name. Stem 2 — 3f high, branching, pubescent when young. 

 Leave3 with segments acute and parallel, i.arren flowers small, green, in ter- 

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



' Sept. (A. elatior Ph.) 



3 A. psylostachya DC. IVJiiiish icilh oppressed woolly hairs, branched ; lya. 

 crowded, rigid, tho lower opposite, bipinnatifid, upper lanceolate, sessile, pin- 

 natifid ; sterile hds. in spicato racemes, fertile clustered at tho baso of tho sterile 

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

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



