238 cOMPOsiTiE. (composite family.) 



2. VERNONIA, Schreb. Iron-weed. 



Heads discoid, 1 5 - many-flowered, in corymbose cymes; flowers perfect. 

 Involucre shorter than the flowers, of many much imbricated scales. Recep- 

 tacle naked. Achenes cylindrical, ribbed ; pappus double, the outer of minute 

 scale-like bristles, the inner of copious capillary bristles. — Perennial herbs, 

 with leafy stems, alternate and acuminate or very acute leaves and mostly 

 purple flowers. Species very difticult. (Named for Wm. Vernon, an early 

 English botanist who travelled in this country.) 



* Heads large, 50- 7 Q-Jioivered. 



1. V. Arkansana, DC. Tall, rather glabrous ; leaves linear-lanceolate, 

 retrorsely denticulate ; involucre very squarrose, the scales with long filiform 

 tips. — Mo., Kan., and southward. 



* * Heads Y ^^^9^1- or less, 15-40-Jloicered. 



H- Leaves narrowly linear, glabrous, veinless, mostly entire. 



2. V. Jamesii, Torr. & Gray. Low, nearly glabrous; heads few-flow- 

 ered ; scales obtuse or acute. — Plains of Neb. and southward. 



H- •<- Leaves broader, mostly sharply denticulate or rigidly serrate, veined. 



3. V. fasciculata, Michx. Leaves linear to oblong-lanceolate; heads 

 many, crowded; scales close, obtuse or the uppermost mucronate"; achene 

 smooth. — Low grounds, Ohio and Ky. to Dak., and southward. Aug. 



4. V. altissima, Nutt. Usually tall ; leaves lanceolate or lance-oblong ; 

 cyme loose ; scales close, obtuse or mucronate ; achenes hispidulous on the 

 ribs. — Low grounds, AV. Penn. to 111., and southward. — Heads variable, 2- 

 4" high and the scales in few or many ranks ; the var. grandifl6ra, Nutt., 

 with large heads, tlie involucre of 35-40 scales in many ranks. 



5. V. Noveboraeensis, Willd. Rather tall ; leaves long-lanceolate to 

 lance-oblong ; cyme open ; involucre usually purplish ; scales ovate and lance- 

 ovate tipped Avith a slender cusp or awn. — Low grounds near the coast, Maine 

 to Va., west to Minn., E. Kan., and southward. Aug. 



Var. latif 6Ha, Gray. Leaves broader ; heads few ; scales merely acute or 

 acuminate. — Penn. to Ohio and southward. 



6. V. Baldwinii, Torr. Tomentulose ; heads small, at first globose ; 

 leaves lance-oblong or -ovate ; involucre hoary-tomentose, greenish, scjuarrose, 

 the scales acute or acuminate. — Prairies and barren hills ; E. Mo. to Kan. and 

 Tex. July, Aug. Passes into n. 4. 



3. SCLEROLEPIS, Cass. 



Head discoid, many-flowered ; flowers perfect. Involucral scales linear, equal, 

 in 1 or 2 rows. Receptacle naked. Corolla 5-toothed. Achenes 5-angled; 

 pappus a single row of 5 almost horny oval and obtuse scales. — A smooth 

 perennial, with simple stems, rooting at the base, linear entire leaves in whorls 

 of 4-6, and a terminal head of flesh-colored flowers. (Name composed of 

 a-K\7}p6s, hard, and Kewls, a scale, from the pappus.) 



1. S. verticillata, Cass. — In water; pine barrens. New Jersey and 

 southward. Aug. 



