American Association at Dubuque. 291 
It would be tedious and except to botanists abstruse to 
enumerate instances, yet the whole strength of the case depends 
upon the number of such instances. I propose, therefore, if 
the Association does me the honor to print this discourse, to 
append in a note a list of the more remarkable ones. But I 
would here mention two or three cases as specimens. 
Our Rhus Toxicodendron or poison ivy, is very exactly re- 
peated in Japan, but is found in no other part of the world, 
although a species much like it abounds in California. Our 
other poisonous Rhus (A. venenata), commonly called poison 
dogwood, is in no way represented in Western America, but 
has so close an analogue in Japan that the two were taken for 
the same by Thunberg and Linneeus, who called them &. vernia. 
ur northern fox-grape, Vitis Labrusca, is wholly confined to 
~ the Atlantic States, except that it reappears in Japan and that 
region. 
The original Wistaria is a woody leguminous climber, with 
showy blossoms, native to the Middle Atiantic States. The 
other species which we so much prize in cultivation, W. Sinensis, 
1s from China, as its name denotes, or perhaps only from Japan, 
where it is certainly indigenous. a spies 
ur yellow wood (Cladrastis) inhabits a very limited district 
on the western slope of the Alleghanies. Its only and very 
near relative (Maackia) is in Mandchuria. : 
he Hydrangeas have some species in our Alleghany region. 
All the rest belong to the Chino-Japanese region and its con- 
tinuation westward. The same may be said of Philadelphus, 
except that there are one or two mostly very similar in Cali- 
ormia and Oregon. 
Our blue cohosh (Caulophyllum) is confined to the woods of 
ly b 
es. 
Another relative is our twin leaf, /efersonia, of the peg ars 
I ought not to omit ginseng, the root so prized by the Chinese, 
Which they obtained from their northern provinces and Mand- 
