222 coiu'OSiXiE. (composite family.) 



2. B. subEC£lulis, Nutt. Kongh-pnbescent and somewhat hoary ; leaves 

 chiefly radical, clustered, sinuate-pinnatitid ; heads solitary on the peduncle-like 

 stem, or few on the peduncle-like branches of the short and nearly leafless stem. 



— East Florida and Georgia. May - August. — Peduncle 6' - 8' long. Leaves 

 3' long. 



34. PARTHENIUM, L. 



Heads many-flowered ; the ray-flowers 5, in a single row, short, obcordate, 

 pistillate ; those of the disk tubular, 5-toothed, sterile. Anthers slightly united. 

 Scales of the involucre in two rows, ovate or roundish. Receptacle conical, 

 chaffy ; the chaff dilated upward. Achcnia smooth, compressed, thick-mar- 

 gined. Pappus of two awn-like or roundish scales. — Herbs. Leaves alternate. 

 Flowers white. 



1 . P. integrifolium, L. Perennial ; stem erect, simple, rongh ; leaves 

 undivided, ovate or oblong-ovate, serrate ; the lowest narrowed into a long 

 petiole ; panicle dense, corj'mbose ; involacre hoary ; pappus minute, awn-like. 



— Dry soil among the mountains, Alabama, and northward. August. — Stem 

 1 ° - 2° high. Lowest leaves 4' - 6' long. Rays conspicuous. 



2. P. HysterophoruS, L. Annual, pubescent ; stem diffuse ; leaves 

 pinnatifid. with linear toothed lobes ; heads loosely panicled ; scales of the pap- 

 pus oval. — Waste places, East and South Florida, and westward. 



35. IV A, L. 



Heads few- or many-flowered ; the flowers all tubular ; the marginal ones 

 (1-5) with a short corolla, pistillate and fertile; the central ones 5-toothed, 

 sterile. Anthers nearly distinct. Scales of the involacre 3-5, in a single row, 

 oval or obovate, distinct or partly united, or 6 - 9 and imbricated. Chaff of the 

 small receptacle linear or spatulate. Achenia biconvex, obovate. Pappus none. 



— Branching herbs or shrubs, with opposite or (the upper) alternate mostly 

 fleshy leaves, and Small axillary nodding heads of whitish flowers. 



* Scales of the involucre 3-5, in a single row. 



1. I. frutescens, L. Shrubby; leaves lanceolate or oblong, sharply 

 toothed-serrate, 3-ribbcd, smoothish ; scales of the involucre 5, orbicular ; fertile 

 flowers 5. — Saline marshes, Florida, and northward. Aug. and Sept. — Shrub 

 4° - 8° high. 



2. I. microcephala, Nutt. Annual, rough with rigid appressed hairs ; 

 stem slender, much branched ; leaves narrow-linear, entire ; heads minute, 6 - 

 12-flowered; scales of the involucre 4 - 5, obovate, ciliate ; fertile flowers 1-3. 



— Dry barren soil, Florida to South Carolina. Aug. and Sept. — Stem 1° - 2° 

 high. 



* * Scales of the involucre 6-9, imbricated in 2-4 rows. 



3. I. irabricata, Walt. Somewhat shrubby, smooth ; leaves fleshy, lance- 

 olate, the lower ones slightly serrate and 3-ribbed, the upper alternate and entire; 

 heads many-flowered ; outer scales of the involucre orbicular ; the inner obovate. 



