628 COMPOSITE. 



scurely denticulate near the apex, the others much smaller, the upper ones 

 (^' or less long) passing into the oblong-llntar obtuse bracts of the widely 

 spreading flat panicle; involucre ovoid, Itj - 20 flowered, the oblong scales 

 obtuse; rays fevf, notched ; pappus coarse, shorter tliau tlie flowers; ovary 

 smooth. — Roclcy barrens of Tennessee [£>r. Gattinger). 



S. rupestris, Raf. Smootli throughout; stem slender (2°-3° high); 

 leaves linear-lanceolate, entire, or the lowest ones slightly serrulate ; panicle 

 narrow, often simple ; heads small with very short rays ; achenia pubescent. 

 — Rocky banks, Tennessee. 



LINDHEIMERIA, Gray & Engelm. 



Ray-flowers 4-5. Scales of the involucre in two rows, the outer ones 

 linear, the inner ones oblong, adherent to the base of the fertile achenia, 

 and to the adjacent scales of the receptacle. Achenium oval, flat, the nar- 

 row wings prolonged into a 2-toothed pappus. Otherwise like Berlandiera. 



L. Tesrana, Gray & Engelm. — Alabama (Mohr), and westward. — An- 

 nual, liirsute, erect, 1° - 2° high. Leaves oblong, dentate. Heads in a dichot- 

 omous panicle, nodding. Flowers yellow. 



IVA, L. 



I. ciliata, Willd. Annual, hispid; stem branching; leaves ovate, acu- 

 minate, coarsely serrate ; spikes dense, the bracts elongated; scales of the 

 involucre S-4, roundish, ciliate ; fertile flowers mostly 3. — Mississippi 

 (Carpenter), and westward. September. — Stem 2°-3° high. Leaves 3'-4' 

 long. 



AMBROSIA, Tourn. 



* * * Heads of slerile flowers densely cpiked, the top-shaped involucre produced on 

 one side into a long recurced appendage. Fertile heads axillary, i-angled. 



A. bidentata, Michx. Annual, hirsute, very leafy ; leaves mostly alter- 

 nate, lanceolate, sessile or clasping, entire or with 2 short basal lobes ; fruit 

 acute, with 4 short spines. — Nortliern Mississippi, and westward. — Stem 

 1° -2° high. 



ACANTHOSPERMUM, Schrank. 



Heads monoecious, radiate, many-flowered ; the rays pistillate, in a single 

 row ; disk-flowers staminate, tubular, 6-toothed. Involucre of 5 elliptical 

 scales. Receptacle flat. Achenia compressed, armed on the back with rigid 

 hooked prickles, and enclosed in tlie outer scales of the chaffy receptacle. — 

 Diffusely branching herbs, with opposite leaves, and solitary heads of yellow 

 flowers. 



A. xanthioides, DC. Prostrate, pubescent ; leaves petioled, oval or 

 obovate, toothed or entire ; chaff of the receptacle which encloses the ache- 

 nium unarmed. — Introduced from South America several years ago, and 

 now widely disseminated. 



