250 COMPOSITE, (composite family.) 



late and fertile ; the disk-flowers staminate with imperfect styles, sterile. Invo- 

 luere heinispherical, of 2 ranks of short ovate or roundisli scales. Receptacle 

 conical, chafiy. Achenia only in the ray, obcomprcssed, surrounded hy a slen- 

 der callous margin, crowned with the persistent ray-corolla and a pappus of 2 

 small chatty scales. — Leaves alternate. Heads small, corynihcd ; the tlowers 

 whitish. (An ancient name of some plant, from napdtvos, vinjin.) 



1. P. integrifblium, L. Kough-puhesccnt perennial (l°-3° high); 

 leaves ohlong or ovate, crenate-toothed, or the lower (3' -6' long) cnt-lohcd he- 

 low the middle ; heads many in a very dense flat corymb. — Dry soil, Maryland 

 to Wisconsin and southward. June - Aug. 



2 9. IV A, L. Marsh Elder. IIiGiTWATER-snRCB. 



Heads several-Howered, not radiate ; the pistillate fertile and the staminate 

 sterile flowei-s in the same heails, the former few (1 -5) and marginal, with a 

 small tubular or no corolla ; the latter with a funnel-lorm 5-toothed corolla. 

 A.nthcrs nearly separate. Scales of the iavoiucre few, roundish, lleceptaclc 

 small, with narrow chaft" among the flowers. Achenia obovoid or lenticular. 

 I'appus none. — Herbaceous or shrubby coarse plants, with thickish leaves, the 

 lower opposite, and small greenish-white heads of flowers ; in summer and au- 

 tumn. (Name of unknown derivation.) 



4 I. Ftrl He flowers irit/i a small, tubular corolla: involucre simple {heads noddimj in 

 the arils of Ifiif-llb' bracts, fi>rmin(/ spikes or racemes). 



1. I. frut6scens, L. Shrubhi/ at the liase, nearly smooth (.3° -8° high); 

 leaves oval or lanceolate, coarsely and sharply toothed, rather fleshy, the upper 

 reduced to linear bracts, in the axils of which the heads are disjwsed, in leafy 

 paniclcd racemes ; fertile flowers and scales of the involucre 5. — Salt marshes, 

 coast of Massiuliusetts to Virginia, and southward. 



2. I. ciliata, WilUl. Annual {2° -8° hh^h), rourjh and hain/ ; leaves ovate, 

 pointed, coarsely toothed, doinnij beneath, on slender cUiate petioks ; heads in dense 

 spikes, with conspicuous ovate-lanceolate rough-ciliatc bracts; scales of .the in- 

 volucre and fertile flowers 3-5. — Moist ground, from Illinois southward. 



$ 2. EUPHIKJSYNE, DC. Fviii I e flow-is 5, in the arils of as mani/ thin mem- 

 branaceous scales of the involucre, ivhich loosely enwrap the achenia, their corolhi 

 a mere rudimei^tary rinrj or none. 



3. I. xanthiif61ia, Nutt. /lHn»n/, tall, ronghish; leaves nearly all oppo- 

 site, hoary with minute down, ovate, rhombic, or the lowest heart-shaped, doubly 

 or ent-toothed, or obscurely lobed ; heads small, crowded in s])ikes or dusters 

 disposed in axilRiry and terminal panicles; bracts inconspicuous. — N.W.Wis- 

 consin (T. J. Ilalc), and northwestward. 



30. AMBROSIA, Toum. Ragweed. 



Sterile and fertile flowers occupying different heads on the s;nne plant ; the 

 fertile 1 -3 together and sessile in the axil of leaves or bracts, at the base of the 

 racemes or spikes of sterile heads. Sterile involucres flatfish or top-shaped, 

 composed of 7-12 scales united into a cup, containing 5-20 funnel-form stam- 



