FLOEA OF THE DISTRICT OF COLUMBIA. 273 



1. VERNONIA Schreb. Iron-weed. 



Pappus purplish; bracts with long slender tips; leaves elongate-lanceolate or narrowly 

 lance-oblong, gradually narrowed at the base 1. V. noveboracensis. 



Pappus yellowish; bracts with short stout tips; leaves ovate-lanceolate, usually ab- 

 ruptly narrowed at the base 2. V. glauca. 



1. Vernonia noveboracensis (L.) Willd. 



Woods and open fields. Aug.-Sept. Eastern U. S. 



2. Vernonia glauca (L.) Britton. 



Woods and open fields. July-Oct. Eastern U. S. 



2. ELEPHANTOPUS L. 



1. Elephantopus carolinianus Willd. Elephant' s-foot. 



Dry or moist woods; common. Aug. -Oct. Eastern U. S. 

 Flowers pale purplish, in small, narrow, crowded heads. 



3. EUPATORIUM L. 



Besides the species listed below, two others have been found here as immigrants, but 

 are probably not estalilished : E. capillifolium (Lam.) Small, with leaves dissected into 

 filiform lobes, native farther south, was collected near Chain Bridge, Va., Oct. 13, 

 1912 {Albert Ruth); E. cannabinum L., native of Europe, with 3-lobed leaves, was 

 found along Hunting Creek, Sept. 4, 1899 (Steele; a single plant). 



Flowers pink or purplish; leaves all or mostly in whorls of 3-7, petioled. Plants tall 



and coarse; bracts imbricate in several rows 1. E. purpureum. 



Flowers white, or in one species blue or violet; leaves mostly opposite, sometimes in 

 whorls of 3 or 4, but then usually sessile, the uppermost leaves sometimes alternate. 

 Leaves conspicuously petioled. 



Flowers blue or violet; bracts with violet tips 14. E. coelestinum. 



Flowers white; bracts with greenish or whitish tips. 



Leaves with minute resin dots, the uppermost leaves alternate; involucre with 

 several small bracts at the base, the large bracts mostly truncate at the 



apex 8. E. serotinum. 



Leaves without resin dots, all opposite; involucre with few or no small bracts 

 at the base, the long bracts obtuse or acute. 

 Leaves thin, the blades mostly 3.5-8 cm. wide, the tips long-tapering, the 



teeth acute; petioles mostly 2.5-5 cm. long 12. E. urticaefolium. 



Leaves thickish, the blades mostly 3-5 cm. wide, acute to very obtuse, not 

 long- tapering, the teeth usually very obtuse; petioles mostly 0.5-1.5 cm. 



long 13. E. aromatlcum. 



Leaves sessile or nearly so. 



Leaves perfoliate (the bases united around the stem) 2. E. perfoliatum. 



Leaves not perfoliate, the bases distinct. 

 Leaves narrowed and acute at the base, or in one species the base often obtuse, 

 but the blades then broadest at or near the middle. 

 Bracts all or mostly very acute, with conspicuous white scarious tips; larger 



leaves often 2.5-3.5 cm. wide 4. E. album. 



Bracts obtuse or rounded at the apex, not whitish or with a very narrow 

 scarious border; leaves all or mostly less than 2 cm. wide. 

 Leaves linear, mostly 1.5-5 mm. wide, entire or the larger ones serrate, 



many of them in whorls of 3 or 4 9. E. hyssopifolium. 



Leaves lance-linear to lanceolate, mostly 7-20 mm. wide, all or most of 

 them serrate. 



69289—19 18 



