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But the travel of weeds is by no means in one direction; the West 
pending some of its worst species in exchange for those con¬ 
tributed from the East; we hear of them in Illinois and Ohio, and 
even as far East as New York. A few recent introductions that 
have not yet spread to any extent are mullein ( Verbascum Thapsus, L.), 
seen only along the railroad at Boulder; jimson-weed or thorn- 
apple ( Datura Stramonium , L.), near Boulder and at Golden along 
the railroad; Canada thistle (Cnicus arvensis, Hoffm.), seen in one 
locality only ; ox-eye daisy ( Chrysanthemum Leucanthemum , L.), re¬ 
ported from the south and near Denver. 
CAPSELLA BURSA-PASTERIS, (L.) Moench. (Plate I.) 
(Shepherd’s Purse.) 
Annual; root leaves clustered, pinnatifid or toothed, stem 
leaves sagittate clasping; flowers white; racemes elongated ; pod 
obcordate-triangular. This weed has a very wide distribution; it 
has followed civilization all over the world. With us it is an an¬ 
noyance in gardens and a pest in fields, doing the greatest injury in 
fields of alfalfa ; it has been sent us from several localities with the 
report that it was running out alfalfa. That it is capable of doing 
this I have seen demonstrated in a road-side piece of alfalfa, which 
in three years has entirely succumbed to the encroachment of the 
shepherd’s purse. The plant is an annual; it may be found in 
flower and fruit from earliest spring until winter, and even all win¬ 
ter when the cold is not too severe. In size it varies greatly from 
2 inches to 2 feet; in irrigated fields it makes a rank growth 
and produces an enormous amount of seed. In order to estimate 
approximately the seed-producing possibilities, a count has been 
made of two average plants ; 60 fruits from one plant gave an 
average of 30.1 seeds; for the other, 25 seeds; the average for both 
plants being 271 seeds to each fruit. On one plant were 951 fruits, 
on the other 952 ; this would give over 26,000. seeds to each plant. 
But this would not fairly represent the possibilities ; the plants were 
not mature;, on one 1,444 buds and flowers were counted, on the 
other 1,499 ; assuming that all of these reach full development, and 
we would have an average of over 66,000 seeds to the plant. Allow 
for accidents and assume 50,000 as the average number of seeds 
produced ; surely this is enough to account for the rapid spread of 
the plant. Multiplication is by seed only; it follows that the way 
to subdue the plant is by preventing the formation and scattering 
of seed; the hoe and the cultivator judiciously used will accom¬ 
plish this. We rate the plant as one of our worst weeds, 
