GATES : THE VALIDITY OF HELIANTHUS II.LINOENSIS 81 
As the plants under consideration were both found in the 
Quercus velutina association where it occurs on sand dunes, it 
seemed well to look into their status during 1908, when the sand 
areas of Illinois were studied by Dr. Gleason. During the early 
part of the summer, plants seemingly belonging to the new species 
were found associated with the Quercus velutina wherever that 
association occurred. The following are a number of localities in 
which this association was studied and from which plants in ques- 
tion were collected : 
St. Anne, Kankakee Co., Ill. (Gaves 2437, 2439.) 
Hanover Station, Jo Daviess Co., Ill. (2662, 2672.) 
Savanna, Carroll Co., Ill. (2684.) 
Oregon, Ogle Co., Ill. (2778, 2733.) 
Winthrop Harbor, Lake Co., Ill. (2774.) 
Beach, Lake Co., Ill. (2749, 2887, 2936, 2965.) 
In addition to these localities observations were made in Rock 
and Kenosha counties, Wisconsin, and McHenry Co., Illinois. 
Nothing seemed to be amiss until near Winthrop Harbor, IIli- 
nois, it was discovered that plants which in the spring and early 
summer were /7/. zl/inoensis, were at the time of blooming and 
fruiting simply 7. occidentalis. This observation led to careful 
study of these plants wherever they were found during the season 
of 1909. The conclusions that were inevitably drawn were that 
HT. illinoensis was an ecological subspecies of A. occidentalis, pro- 
voked in response to severer xerophytic conditions or increased 
food supply. Accordingly I propose that these plants should bear 
the name: 
Helianthus occidentalis illinoensis (Gleason) Gates, comb. nov. 
Helianthus tllinoensis Gleason, Ohio Nat. 5: 214. 1904. 
Helianthus occidentalis grows both in the black soil prairies of 
Illinois, etc., and in the sand areas which are distributed over the 
north and central parts of Illinois. In so far as could be observed 
those plants of this species growing in the black soil prairies 
showed no indications whatsoever towards modification in the 
direction of the subspecies. The latter is a plant of sand regions, 
but the mere growing of the type in sand does not necessarily 
mean that any characters of the subspecies will appear. In all 
