BIG SPRING PRAIRIE. io 
Hoar-hound); Eupatorium perfoliatum (Boneset); Poten- 
tilla monspeliensis (Bushy Cinquefoil); Aster vimineus 
(Small white Aster). 
The following occur stillless frequently: Rosa car- 
olina, Asclepias tuberosa, Onagra biennis, Carduus mu- 
ticus, Iris versicolor, Sambucus canadensis, Urtica gra- 
cilis. From the cultivated ground the following are the 
most plentiful: Achillea millefolium (Millfoil or Yar- 
row); Dipsacus silvestris Mill. (Wild Teasel); Oxalis, 
{two species) Ambrosia artemisiaefolia (Bitterweed, 
Ragweed); Chenopodium album L. (Lambs-quarters); 
Amerantus retroflexus L. (Rough Pigweed); Nepeta 
cataria L. (Catnip); Rumux crispus L. (Curled Dock); 
Polygonum hydropiper L. (Water-pepper); Polygonum 
persicaria L,. (Lady’s thumb); Leptilon canadense (L.) 
Britt. (Horse-weed) and Convolvulus sepium L. (Hedge 
Bind-weed). In the eastern portion of field, there 
are a few Crataegus and one specimen of Gleditschia 
triacanthus. 
The introduced species in this field occur most 
commonly where there are breaks in the sod or upon 
the soil thrown from the ditches. A dense sod seems 
to be an effectual preventative against the encroach- 
ment of most species of plants. ‘The plants which will 
gain a foot-hold upon the suitable places are chiefly 
those which occur on the areas around it tothe windward, 
and under similar ecological conditions of soil, moist- 
ure, etc- This fact is strikingly illustrated in compar- 
ing field H, a natural grassy meadow along the western 
border of prairie, with artificial meadow A in the east- 
ern portion. Fields F and B are closely allied in phys- 
ical and chemical characteristics of soil to field A, and 
the wind is suitable for seed dissemination, in conse- 
quence, we find many species in common. 
FIELD H. 
This is a natural meadow. It is strikingly differ- 
ent in physical and chemical characteristics of soil from 
