136 Cincinnati Society of Natural History. 



DISFRIBUTION OF VERNONIA IN THE UNITED 

 STATES. 



BY PltOFKSSOR JOSEPH F. JAMES, M.SC, MARYLAND AGRICUL- 

 TURAL COLLEGE. 



Read by Title December 4, 1888. 



The genus Vekmomia, named for Wm. Vernon, an early English 

 collector of plants in Virginia, includes what are commonly called 

 the "Iron-weeds." 'I'he common name has probably arisen from 

 the tough nature of the stem, noticeable in most of the species. The 

 genus is a large one, containing over 400 species ; its headquarters 

 is in South America, but it extends into North America, and has a 

 few Asian and African, but no European, species. As given in the 

 last edition (5th) of Gray's Manual, there are but two species in 

 the north-east United States. The Synoptical Flora of the same 

 author adds one species and two varieties to these. The additions 

 are variety iatifolia, Gr. , of Noveboracensis, altissinia, Nutt. , and 

 altissinia var. grandi^ora, Gray. 



Tiie ji.eoyrapliical distribution of tlie species is interesting. Two, 

 or possibly three, Noveboracensis, fascicnlata and altissinia, are widely 

 scattered : the rest are local, some extremely so. Some of these 

 are confined to the country west of. the Mississippi, some to that 

 part south of Tennessee and North Carolina. None grow farther 

 north than Vermont or Massachusetts (although one species is found 

 in Canada), in the east, nor Dakota in the west, and none are 

 found farther west on the south than New Mexico, nor on the 

 north, west of Kansas. Colorado and all the country westward has 

 no species, nor indeed any closely-allied form. Most of the species 

 grow in wet or at least damp soil, sometimes even in swamps, only 

 few being found in dry soil, and these being very local. Oat of 

 the fifteen species and varieties credited to the United States, only 

 five, one-third of the whole, are given as inhabiting dry soils or 

 plains. This almost constant association with damp places seems 

 to fully account for the absence of any species in the west, where 

 dryness generally prevails. The further fact that the genus is one 



