GLEASON: TAXONOMIC STUDIES IN VERNONIA 245 
replaced by short straight conical hairs. The leaves are smaller 
and proportionately narrower, and frequently with a basal taper. 
Because of these structures, the species is frequently mistaken for 
V. altissima Nutt., from which it may be distinguished by the 
resin-dots on the leaf, involucral scales, and achenes. This 
extreme form has been described by Daniels under the name V. 
michiganensis, and the same thing from Ontario appears in several 
herbaria under another unpublished name. 
Throughout this whole region, from Michigan to Missouri, 
the plants exhibit generally rounded to subacute, purple involucral 
scales, imbricate in relatively few series, and a purple pappus. 
This is the form described by the writer as V. illinoensis. 
West of this region the species is much less common, and the 
herbarium material has been collected in widely scattered localities 
as far south as southern Texas. In general, the collections from 
west of the Mississippi and south of the Missouri Rivers have a 
loose open inflorescence, sharper and frequently smaller involucral 
scales, imbricate in relatively many series, and frequently green 
instead of purple, and a pappus which soon becomes tawny in 
color when exposed to light. But these differences are not con- 
stant nor even coincident on the same plant, so that even well- 
marked varieties can not be accurately distinguished. Yet in 
four cases out of five the geographical origin can be correctly 
guessed merely by a glance at the involucre of the plant. 
Another area in which a form of the species occurs is the coastal 
region of southern Mississippi and Alabama. Whether similar 
plants also occur in southern Louisiana and southeastern Texas 
is not known definitely, but the inference is that they do. This 
extreme southeastern form differs in certain features from the 
species, so that it is recognizable at a glance, and it may be de- 
scribed as a variety. 
Vernonia missurica austroriparia var. nov. 
Inflorescence more or less elongate, very loose, open, irregular, 
and few-headed; leaf-blades broadest distinctly above the middle, 
thinly tomentose beneath or merely pubescent; resinous glands 
on the leaves, scales, and achenes as in the typical form of the 
species. 
