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are foreign. In New Jersey, as appears from Dr. Halstead’s weed 
list, the foreign and native species are almost equally divided. 
That the Eastern States should have a larger proportion of 
European weeds than the Western, is perfectly reasonable ; they 
have a much older agricultural development, are nearer the ports 
of entry, and the advantages for the growth and dissemination of 
plants have been greater. Considering the comparatively short 
period since cultivation of the soil began in Colorado, we have a 
remarkably large representation of European weeds, and we are 
yearly receiving additions. Our large percentage of native weeds 
may also be accounted for by the nature of the country. Dr. Gray, 
in an article on weeds, explained that the herbaceous plants native 
in the forest-covered East, were placed at a disadvantage by the 
removal of the forests, and could not successfully compete in the 
struggle for existence with the introduced European weeds. In 
our Western treeless region the native plants are subject to full 
exposuie, and have become inured to the most adverse conditions. 
Cultivation and irrigation have given them new vigor; they no 
longer merely exist—they assert themselves, and find place among 
the most aggressive of our weeds. 
Arranging our weeds according to their duration, we find that 
128, or more than one-half, are perennials. Of these, 98 are native, 
and 30 are foreign. The biennials are represented by only 11 
species, 7 of which are foreign. The 89 annuals are quite evenly 
divided, 43 being foreign, and 46 native. 
Division according to relative badness is of necessity entirely 
arbitrary ; an attempt has been made to base the position of each 
species upon the sum of its bad qualities. There is with many , 
species a single quality which predominates over all others, and 
determines its position ; one species, by reason of its prolificacy, 
may be ranked as one of the worst; another, much less abundant, 
may take the same rank because it is very persistent and difficult 
to eradicate. Our present estimate places in the list of worst 
weeds 56 species; 29 of these are foreign and 27 native. The 
species falling under the head of bad weeds number 81, 55 of 
which are native, and 26 foreign. In the list of indifferent weeds, 
the predominance of native species is still further increased, there 
being 66 native and 25 foreign, a total of 91. 
Classified botanically, our weeds have a wide distribution. 
The 228 species and varieties represent 141 genera, belonging to 
42 orders. Compositse has much the largest representation; 55 
species and varieties, or very nearly one-quarter of the whole, be¬ 
long to this order; next come Leguminosa3 and Graminese, repre¬ 
sented by 12 genera and 21 species each ; then follows Polygonacese, 
with 16 species; the balance are distributed in numbers varying 
from 1 to 8. 
