178 
IOWA ACADEMY OF SCIENCE 
These general observations then show that vegetation in the vicinity 
of manufacturing concerns shows the effects of the fumes and smoke 
emitted. It also appears that some species are more susceptible than 
others. 
SURVEY AREAS — FLORAL DEMARKATIONS. 
When general observations were made in the early part of June of 
fast year, certain demarkation features, imparted by the flora itself, 
were present. The absence of a certain form in one portion and the 
presence of a form in another area, providing the sarnie ecological fea- 
tures, immediately led one to conclude that, the absence or pathological 
presence is brought about by the gaseous emanations from mills or other 
manufacturing concerns. In order to ascertain this feature more defi- 
nitely, two restricted areas were chosen, one in the vicinity of the Illinois 
Steel Co., and the other in the vicinity of the Wisconsin Steel Co. 
For the purpose of reference as well as convenience, it was thought 
advisable to have a number of belts or zones and each belt to be repre- 
sented by a numeral as well as by the outstanding floral representative 
or representatives. These belts are as follows: (1) Restricted annuals, 
(2) Numerous annuals, (3) Willows, (4) Cottonwoods, (5) Burr Oaks, 
(6) Other deciduous trees, (7) Conifers, (8) Pleurococcus. 
The first belt* known as belt (1) is the result of a gradual elimination 
stage in the general process. The zone is not very extensive in area 
and the species are not large in number. Four outstanding species were 
present. Prostrate pigweed ( Amaranthus blitoides Wats.), fescue 
grass ( Festuca ovina L.), milk purslane ( Euphorbia maculata L.), old 
witch grass ( Panicum capillar e L.). Even these forms are stunted in 
size, and often are in such shape as to be extremely hard of identification. 
The next belt includes the forms of the previous one but they are 
much more vigorous and considerably truer to type. In addition, the 
following are conspicuous: cockle bur ( xanthium canadense Mill), 
ragweed ( Ambrosia artemesiifolia L.), yellow fox tail ( Setaria glauca 
(L.) Beauv.), green fox tail {Setaria verdis (L.) Beauv.), hedge 
mustard {Sisymbrium altissimum L.), rough pig- weed {Amaranthus 
retroflexus L.), barnyard grass {EchinocMoa crusgalli (L.) Beauv.), 
begar’s ticks (Bidens frondosa L.), squirrel tail grass {Hordeum 
jubatum L.), Russian thistle {Salsola Kali var tenuifolia G. F. W. Mey.). 
This belt has an area extending approximately from Harbor Ave. and 
The Strand to Mackinaw Ave. In the instance of the Wisconsin Steel 
* These zones are marked out in the accompanying map. By using the general 
standard of eight blocks to the mile a good idea of the distance is obtained. 
