The validity of Helianthus illinoensis Gleason as a species 
FRANK C, GATES 
The plants to which the name Helianthus tllinoensis Gleason 
was assigned were collected by Dr. H. A. Gleason on sand dunes 
along the Illinois River near Havana, Illinois, during 1903 and 
1904, where they occur in the Quercus velutina association. The 
original description was published in the Ohio Naturalist (5: 214. 
1904) and reprinted in “On the biology of the sand areas of 
linois”” by C. A. Hart and H. A. Gleason (Bulletin Illinois State 
Laboratory of Natural History 7: 188. Ja 1907). The salient 
points in the description are as follows: 
“‘ Erect, six to ten dm. high, from a long running rootstock. 
Stem simple, slightly angled, densely villous below, pubescent 
above. Leaves six to eight pairs, strictly opposite, slightly sca- 
brous above, softly pubescent beneath and villous on the veins, 
obtuse ; the lowest four or five pairs oblong-lanceolate to ovate- 
lanceolate, three-nerved, entire, ten to fifteen cm. long, tapering at 
the base into a winged petiole equaling or but little shorter than 
the leaves ; the upper two or three pairs much smaller or bract- 
like, petiole short or none. Lower internodes five to eight cm. in 
length, or the two lowest pairs of leaves approximate, upper inter- 
nodes much longer. .. . Flowers in August. . . . Helzanthus 
wlinoensis is evidently closely related to Helianthus occidentalts 
Riddell, which it resembles in the reduction in size of the upper 
leaves. It is at once distinguished from the latter species by the 
villous pubescence and the greater length of the lower internodes. 
The two are sometimes associated in the field, but in general 
appearance they are entirely distinct. Helianthus occidentalis has 
broad, scabrous, light green, short-petioled leaves which are nearly 
erect in a basal cluster, while in Helianthus illinoensis they are 
darker green, more or less spreading and scattered on the stem.’ 
The corresponding features of Helianthus occidentalis Riddell 
are thus characterized in Britton’s Manual : 
“Stems appressed-pubescent or sometimes nearly glabrous, 
slender, mostly simple, 6-9 dm. high. Leaves mainly basal, firm, 
ovate or oblong-lanceolate, obtuse or obtusish at the apex, nar- 
rowed at the base, 3—5-nerved, serrulate or entire, mostly scabrous 
above, pubescent beneath, with slender petioles.” 
