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there generally occurred many more in the same immediate 
neighborhood. The Dalea alopecuroides . (Willd.), which I met 
with but once, was found in that locality in the greatest abun¬ 
dance. The Sature.ia hortensis . which I believe is not regard¬ 
ed as indigenous to North America, was seen once by us in 
the greatest profusion, and that, too, in a situation the least 
favorable to the idea of its having been introduced—the 
centre of a large prairie, where no settlement could have 
been made. At some places between Peoria and Springfield 
the road-sides and even the beaten path, were so completely 
covered over with the little Boebera chrysanthemoides . that, 
trodden under our horses 1 feet, it exhaled a strong and nause¬ 
ating odor. In many such localities this noisome weed seems 
to take the place of the Anthemis cotula and JU arvensis (May¬ 
weed and Dog-fennel,) in the more settled portions of the 
Western States. In the neighborhood of Springfield, again, 
and especially in the out-lots of that town, we found the 
ground covered, to the exclusion of almost every other vege¬ 
tation, with a small species of Ambrosia (A. bidentata ) which, 
at the season in which we saw it, being out of flower, and 
ripening its dark-colored seed, gave to the common an aspect 
as dreary as "the bleak and blasted heath where Macbeth met 
the witches." In illustration of this peculiarity of the Bota¬ 
ny of the prairies, I will only further remark that we did not 
observe the little Erigeron divaricatum until we reached Bloom¬ 
ington, in the commons of which town it is extremely abun¬ 
dant; and that it ceases to occur, or is but rarely seen, a few 
miles south of that. 
There are, indeed, comparatively speaking, but few plants, 
except the grasses, (which are gregarious every where, 
and aj?e intermixed in greater or less degree and variety 
among all the other plants of the prairies,) which may be 
considered as indigenes of the prairie region generally.— 
Among these we may mention, as occurring most constantly, 
and under greater diversity of soil and situation than any 
others, the Silphium gummiferum . Parthenium integrifolium , 
Kuhnia critonia . Ceanothus intermedius . (which here takes the 
