260 COMPOSITE, (composite pamilt.) 



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

 lucre hemispherical, of 2 ranks of short ovate or roundish scales. Receptacle 

 conical, chaffy. Aehenia only in the ray, obcompressed, surrounded by a slen- 

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

 small chaffy scales. — Leaves alternate. Heads small, corymbed ; the flowers 

 whitish. (An ancient name of some plant, from nap6evos, virgin.) 



1. P. integrifdlium, L. Rough-pubescent perennial (l°-3° high) ; 

 leaves oblong or ovate, crenate-toothed, or the lower (3'- 6' long) cut-lobed be- 

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

 to Wisconsin and southward. June - Aug. 



29. IV A, L. Mahsh Elder. Eighwatee-sheub. 



Heads several-flowered, not radiate ; the pistillate fertOe and the staminate 

 sterile flowers in the same heads, the former few (1-5) and marginal, with a 

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

 Anthers nearly spparate. Scales of the involucre few, roundish. Receptacle 

 small, with narrow chaff among the flowers. Aehenia obovoid or lenticular. 

 Pappus 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.) 



§ 1. Fertile Jhwers with a smaU tubular corolla: involucre simple {heads nodding in 

 the axils of leaf-like bracts ^foi-ming spikes or racemes). 



1. I. frut6scens, L. Shrubby at the hose, 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 disposed, in leafy 

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

 coast of Massachusetts to Virginia, and southward. 



2. I. eiliita, WiUd. Annual (2° -&° 'ingh), rough and hairy ; feares ovate, 

 pointed, coarsely toothed, downy beneath, on slender ciliate petioles ; heads in dense 

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

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



§ 2. EUPHROSYNE, DC. Fertile flowers 5, in the axils of as many thin mem- 

 branaceous scales of the involucre, which loosely enwrap the aehenia, their corolla 

 a mere ntdimentary ring or none. 



3. I. xanthiifdlia, Nutt. Annual, tall, roughish ; leaves nearly all oppo- 

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

 or cut-toothed, or obscurely lobed ; heads small, crowded in spikes or clusters 

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

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



30. AMBROSIA, Tonm. Ragweed. 



Sterile and fertile flowers occupying different heads on the same 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- 



