CAKDUACEAE 1235 



Plants annual. 



Bracts of the involucre thin, sparingly pubescent. 5. P. petiolata. 



Bracts of the involucre thick, densely pubescent. 

 Leaves not decurrent on the stem. 



Involucres 4-5 mm. high or less, 3-4 mm. wide. 6. P. purpuraeceM. 



Involucres 6-8 mm. high, 6-7 mm. wide. 7. P. camphorata. 



Leaves decurrent on^the stem as wings. 8. P. Quitoc. 



1. Pluchea odorata Cass. Perennial, closely pubescent. Stems several dm. tall, 

 woody : leaf -blades oblong or nearly so, 8-15 cm. long, obtuse or apiculate, entire, peti- 

 oled : heads numerous, in rounded corymbs : involucres 2-2.5 mm. high ; bracts oblong or 

 slightly broadened upward, pubescent, ciliate, obtuse : achenes. 



In sandy soil, peninsular Florida and the Keys. Also the West Indies, Central and northern South 

 America. Throughout the year. 



2. Pluchea foetida (L.) B.S.P. Perennial, minutely pubescent. Stems 3-10 dm. 

 tall, simple or branching above : leaf-blades oblong to ovate-oblong, 3-8 cm. long, acute, 

 serrate, sessile and clasping : heads in sessile or short-peduncled clusters : involucres cam- 

 panulate, 4 mm. high : bracts oblong to linear or narrowly linear-lanceolate, the inner 

 acute, the outer acuminate, ciliate near the tips : corollas of the pistillate flowers 3 mm. 

 long. IP. bifrons DC.] 



In low grounds, New Jersey to Florida and Texas. Spring and summer. 



3. Pluchea longifolia Nash. Perennial, softly pubescent, densely so above. Stems 

 6-10 dm. tall, bran ching above : leaf -blades firm, oblong, 5-16 mm. long, mucronate, un- 

 evenly toothed, sessile and partly clasping, the upper ones but little shorter than the lower : 

 heads numerous in rather dense terminal clusters : involucres campanulate, 7-10 mm. 

 high ; bracts broadly ovate to linear, ciliate, the outer obtuse or apiculate, the inner acute 

 or slender-apiculate : corollas of the pistillate flowers 6 mm. long : pappus white. 



In swamps, peninsular and middle Florida. Summer. 



4. Pluchea imbricata (Kearney) Nash. Perennial, finely pubescent and somewhat 

 resinous. Stems 1-2.5 m. tall, branched above: leaf -blades ovate-oblong to triangular- 

 ovate, 3-6 mm. long, firm, mucronulate, rather coarsely serrate, sessile and partly clasp- 

 ing, the upper ones much shorter than the lower, the nerves prominent and red beneath : 

 heads numerous, in dense terminal clusters : involucres campanulate, 7-8 mm. high ; 

 bracts oblong to linear-lanceolate or linear, the outer obtuse, the inner mucronate : corol- 

 las of the pistillate flowers 6 mm. long : pappus buff. 



In swamps or borders of ponds, Georgia and Florida. Summer. 



5. Pluchea petiolata Cass. Annual, puberulent or finely pubescent. Stems 5-11 

 dm. tall, more or less branched : leaves numerous ; blades elliptic or narrowly elliptic, 8- 

 25 cm. long, thin, acuminate at both ends, rather coarsely, serrate-dentate, petioled : heads 

 numerous : involucres campanulate or ovoid-campanulate, 3.5-4 mm. high ; bracts granu- 

 lose, ovate to oblong or nearly linear, acute to acuminate, ciliolate : corollas of pistillate 

 flowers 3 mm. long : pappus whitish, sometimes purple-tinged. 



In moist soil, Virginia and Illinois to Florida and the Indian Territory. Summer and fall. 



6. Pluchea purpurascens (Sw. ) DC. Annual, finely pubescent and somewhat 

 glandular. Stems 3-14 dm. tall, branching above : leaf-blades ovate-lanceolate to elliptic 

 or oblong, 4-10 cm. long, rather blunt, coarsely crenate, short-petioled : heads few or 

 numerous : involucres 3.5-4 mm. high : bracts granulose, oblong to narrowly linear-lanceo- 

 late, ciliolate, the outer mucronate, the inner acute or acuminate : corollas of the pistil- 

 late flowers about 3 mm. long. 



In sandy soil, Georgia and Florida to Texas. Also in tropical America. Summer and fall. 



7. Pluchea camphorata (L. ) DC. Annual, puberulent. Stems 3-15 dm. tall, 

 corymbosely branched above : leaf-blades thickish, elliptic, lanceolate or oblong, 3-15 cm, 

 long, acute, irregularly serrate, usually petioled on the lower part of the stem : heads nu- 

 merous, light purple : involucres hemispheric, about 5 mm. high ; bracts puberulent, ob- 

 long, acute or acuminate, ciliate : corollas of the pistillate flowers 3 mm. long. 



In salt marshes, Massachusetts to Florida, Texas and Mexico. Summer and fall. 



8. Pluchea Quitoc DC. Annual, puberulent. Stems 7-20 dm. tall, branched, winged 

 by the decurrent leaf bases : leaf-blades oblong, narrowly elliptic, lanceolate or linear- 

 lanceolate, 4-16 cm. long, finely toothed : heads numerous, pale purple : involucres 4-6 

 mm. high, the bracts more or less lacerate in age. 



In marshy places, about Pensacola, Florida. Native of tropical America. 



62. CHAENOLOBUS 



Perennial or sometimes biennial caulescent herbs, with tomentose or woolly foliage. 

 Leaves alternate : blades entire, often glabrate above, decurrent on the stem. Heads dis- 



