164 
and other recently introduced forms this fact is very apparent. Local 
conditions may modify this movement somewhat. Thus in the north- 
western counties of the State the movement of the plants, especially those 
of the sand soils is to the south and southeast because of the winds from 
Lake Michigan. The very slight overlap of the characteristic prairie 
flora of Illinois into corresponding regions in Indiana is well known, and 
has its explanation in the above facts. An examination of the flora of 
the State, and a consideration of the mass distribution of the forms in- 
volved shows that a very large proportion of it is from the east and south- 
east, very little from the west. Marked overlaps occur with the true 
southern forms in the southwestern counties, and with northern forms 
in the Lake region, but this is to be expected from the topographical and 
hydrographical features of the regions. 
The weeds of the State have received much attention, and while a 
full treatment of the subject is reserved for the final report of this divi- 
sion of the survey, a few facts are here given in the hope of securing ad- 
ditional data bearing upon this very important subject. 
Salsola kali tragus (.) Moq., the Russian thistle has not spread to 
any great degree. As indicated in a former paper,* its appearance in 
Lake and Noble counties was reason for the belief that its distribution in 
the State would be limited, a belief happily justified by the facts. Its 
disappearance from the regions in which it is now found is but a question 
ci time. 
Lactuca scariola L., the prickly lettuce, is rapidly spreading through- 
out the State and is becoming one of our most dangerous forms. It 
spreads with extreme rapidity and by its rank growth shades out many 
smaller forms and takes sole possession of large tracts. In a piece of 
waste land covering about ten acres, I noted, three years ago, perhaps a 
half dozen plants. Last year the land was entirely taken by the lettuce. 
None of our weeds demands more vigorous measures for its repression, and 
its first appearance in any region should be the signal for the beginning 
of repressive measures. 
Solanum rostratum Dunal, widely heralded a few years ago as a dan- 
gerous weed, has not spread widely and is practically confined to the re- 
gions in which it first found lodgment. It was first reported from Vigo 
and Sullivan counties having come in from the west, and this position 
egies Ee ae i ae a eee 
* Noteworthy Indiana Phanerogams, Stanley Coulter, Proceedings Indiana Academy 
of Science, 1895, p. 192. 
