10 
THE AMERICAN BOTANIST. 
position of comparative insignificance. What were the 
causes which led to their sudden rise to a position of 
prominence and as sudden decline we may not be able to 
tell. We can onh- point out a few of the probable factors. 
Being annuals and requiring plenty of room to grow they 
were easily kept down and all but crowded out of their 
prairie homes by other and hardier plants. They must 
grow and reproduce their kind as best they can under 
the relentless sway of the world wide dominatic n of the 
grass family. Where passing hoofs had tramplec out the 
sod or some burrowin-jr ' ' ' ' ' nionnd 
of earth they found r« ' r two 
till the grass came bac ; 
Through ages ot : they 
doubtless developed t:i ■ 
duce a great number < ; 
vitality that they co':' 
bide their time. The r- - 
wrought by the bre?!]-; 
tumbleweeds of all T.li> 
profit by the overthr 
which had lain for ye.: . : 
and grew into phmts i j 
stirface rich with dc .ctiy 
suited to their needs ■ 
Like barbarian h> . , v rumlj- 
ling Roman Empire tile- • , - . >.iLinto 
places where they had never grown betore. In \ ast wind- 
ciriven armies they began to push out to all points ot the 
compass, each year widening the area of their realm as 
though they had dreamed of universal dominion. Cross- 
ing the Mississippi they encircled the Great Lakes, climbed 
the slopes of the Appalachians and reached the Atlantic 
But ere they reached the sea they had plainly had their 
day. The older soil seemed less suited to them and they 
did not endure cultivation well. Besides they now no 
longer had things all their own way. In the Eastern 
