1014 



COMPOSITAE 



Prenanthes 



30 



Map 2231 

 Prenanthes allissima L. 



The size and vigor of the plants sent me, being much branched and 

 over three feet high, suggest that it is well established and will be able 

 to compete with any native vegetation and forever be a weed in our state. 

 I collected it in the same area in 1937. 



Nat. of Eu. ; no recent distribution given for the U. S. 



9606. PRENANTHES [Vaill] L. 



Involucre glabrous. 



Inner bracts 5; flowers 5 or 6; pappus of mature achenes light brown (Antimony 



Yellow to Ochraceous-Buff of Ridgway, Standard.) 1. P. altissima. 



Inner bracts 6-8; flowers 8-12. 



Involucre greenish white 2. P trifoliolata. 



Involucre purple tinged; plant glaucous 3. P. alba. 



Involucre pubescent. 

 Heads 8-16-flowered. 



Stems and lower surface of leaves glabrous; flowers purplish 4. P. racemosa. 



Stems and lower surface of leaves rough-pubescent; flowers cream color 



5. P. aspera. 



Heads 25-35-flowered ; flowers cream color 6. P. crepidinea. 



1. Prenanthes altissima L. Map 2231. Doubtless formerly found in 

 every county of the state. It is a woodland plant, preferring dry soil, and 

 found principally in oak woods and less frequently in beech and maple 

 woods. The great variation in the shape of the leaves of this species and 

 the two following has led to the naming of several varieties, none of which 

 I consider worthy of a name. I have found the most diverse forms in the 

 same colony. The blades may be undivided, merely dentate, parted with 

 the divisions not stalked, divided into three parts with the two lateral ones 

 stalked and often deeply parted or deeply lobed, cordate or cuneate at the 

 base, and there are many intermediate forms. 



The pappus of the species varies somewhat in color but no plants have 

 been found with a white or even of a sordid color. It is to be noted that 

 the pappus does not acquire its characteristic color until it is mature. 

 Fernald described a variety of this species with cinnamon brown pappus 



