MONOPETALOUS EXOGEliOUS PLANTS. 359- 



ERECHTHITES, Eaf. Fireweed. 



Heads many-flowered ; discoid ; the marginal flowers 

 pistillate, very slender, 2-3-tootlied ; the others perfect, 

 4-5-toothed ; scales of the cylindrical involucre in a single 

 row, linear, acute, bracted ; receptacle naked ; achenia ob- 

 long, striate ; pappus of copious soft hairs. — Erect annual 

 herhs, with alternate simple leaves, and corymbose heads 

 of greenish flowers. 



E. HIERACIFOLIA, Raf. Stem mostly branched, smooth 

 or hairy; leaves lanceolate, sessile, sharply serrate or tooth- 

 ed, the upper somewhat clasping ; bracts subulate, minute ; 

 papptus white. (Senecio hieracifolius, L.) Stem l°-5° 

 high. 



OACALIA, L. 



Heads 5-many-flowered ; the flotoers all tubular and 

 perfect, 5 cleft ; scales of the involucre 5-30, in a single 

 row; receptacle flat, naked, or with a tubercular prominence 

 in the center ; achenia oblong, smooth ; pappus of numer- 

 ous capillary bristles. — Perennial, mostly smooth and tall 

 herlSf with alternate entire or lobed leaves, and corymbose 

 heads of white flowers. 



* Receptacle flat ; involucre about Vi-kaved, 25-^0-flow(red. 



C. SUAVEOLENS, L. Smooth ; leaves ovate, hastate, acute, 

 toothed-serrate, on winged petioles, the uppermost sessile ; 

 bracts filiform. Steiii 3°-5° high. 



** Receptacle tubercular in the center; scales of the involucre and flowers 5. 



C. RENiFORMis, Muhl. Stem angled ; leaves not glau- 

 cous, angularly toothed, on slender petioles, the lowest 

 large, reniform, the upper ones roundish; corymb com- 

 pound. Stem 4°-9° high ; radical leaves sometimes 2° iu 

 diameter, the teeth mucronate. 



C. ATRiPLiciFOLiA, L. Stem terete, corymbosely branch- 



