GILMORE] TAXONOMIC LIST OF PLANTS 61 
have been overgrazed until the original balance of vegetation has 
been destroyed by the unnatural competition induced among the 
native species as well as by the added competitive factor of intro- 
duced species. Thus many pasture lands may now be seen in which 
hard and bitter species, such as Solidago rigida and Vernonia 
fasciculata, not desired by grazing animals, have inordinately in- 
creased. Not only have some species of the natural prairie flora 
been thus decreased and others increased, but the woodland flora 
has been considerably augmented not only by artificial planting, 
but also by attendant protection of the natural increase, which 
protection has been in some instances intentional and in others only 
coincidental. 
The introduction and dissemination of species by human agency 
in aboriginal time has been discussed already. It remains to notice 
the human factor in depletion of certain species and augmentation 
of others prior to European advent. Probably the chief means 
employed by the tribes, affecting the floral balance, was that of 
fire. Their habit of firing the grasslands was effective in retarding 
the advance of woodland with all its associate flora and very 
probably even drove back the forest line and exterminated some 
areas which, previous to any human occupancy, had been possessed 
by forest growth. 
TAXONOMIC LIST OF PLANTS USED BY. INDIANS OF 
THE MISSOURI RIVER REGION? 
PROTOPHYCEAE AND ZYGOPHYCEAE 
Without specification of genera or even of orders it is sufficient 
to say that a green stain for decoration of implements made of 
wood was obtained from masses of the green aquatic vegetation pop- 
ularly known as “pond scum” or “ frog spit.” The green substance 
used by the people of the tribes for the purpose of making a green 
stain, obtained by them from sluggish streams and ponds, doubtless 
consisted of colonies of Protococcus, Ulothrix, Chaetophora, Spiro- 
gyra, ete. 
AGARICACEAE 
Prevrotus utmarius Bull. Elm Cap. 
This fungus is used for food by the tribes acquainted with it. 
When young and tender it is most delicious. It grows in decayed 
spots on Acer negundo and Ulmus sp. The writer discovered its use 
for food among the people of the Dakota Nation. Some women were 
gathering it in a grove of boxelder near the place where the Cannon- 
ball River flows into the Missouri River, and they gave information 
1 See glossary of plant names, p. 139. 
