222 COMPOSIT/K. (cOMrOSITK FAMII.V.) 



2. B. SUbacaulis, Nutt. Rou;;li-pul)Csccnt and Sfjimwlint hoary ; leaves 

 chiefly radiial, ehistcred, siiiuate-piiuuititid ; licads Kolitary on tlie peduncle-like 

 stem, or fow on the jieduncle-Iike hraiu-l)0,s of the sliort and nearly leaHess stem. 



— East Florida and (Jeorgia. May - August. — Peduuele 0' - 8' long. Lcaveu 

 3' long. 



34. PARTHENIUM, L. 



Heads many-flowered ; the ray-flowers 5, in a single row, sliort, ohcordate, 

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

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

 chaffy ; the chaflP dilated upward. Achenia smooth, compressed, thick -mai'- 

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

 Flowers white. 



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

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

 petiole ; panicle dense, corymbose ; involucre hoary ; pappus minute, awu-like. 



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

 l°-2°liigh. Lowest leaves 4' - 6' long. Kays conspicuous. 



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

 pinnutifid. with linear toothed lobes ; heads loosely paniclcd ; scales of the pap- 

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



35. IVA, 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 involucre 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. Pai)pus none. 



— Branching herbs or shrubs, with opposite or (tlie 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. Slirubby; 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 witii 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 l°-2° 

 high. 



* * Scales of the involucre &- 9 , imbricated in 2-4 ivirs. 



3. I. imbricata, Walt. Somewhat shrubby, smooth ; leaves flesh}', 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, 



