Apr., 1923] GLEASON—VERNONIA IN NORTH AMERICA I99 
the pappus is tawny or almost white, and the involucral scales are long- 
acuminate or almost filiform. The leaves are large in proportion to the 
height of the stem, and the greatest expanse of foliar surface is toward the 
base of the stem. While this feature is apparent in V. glauca (L.) Willd., 
an Alleghenian species ranging northward to Pennsylvania, it is still further 
developed in V. acaulis (Walt.) Gleason and V. georgiana Bartlett, two 
coastal plain species with distinctly basal leaves. 
Two other species with prolonged filiform scales constitute the group 
Noveboracenses. V. noveboracensis (L.) Michx. has attained a wide dis¬ 
tribution over the Piedmont region of the eastern states from Mississippi 
to Massachusetts, occasionally invading the coastal plain also. There it has 
given rise to a localized species, V. Harperi Gleason, characterized by larger 
heads with more numerous flowers. 
V. gigantea (Walt.) Britton is closely related to V. concinna Gleason, 
of the Angustifoliae, and like that species is confined to the southeastern 
portion of the coastal plain. 
The last species-group of the southeastern states is the Altissimae. V. 
ovalifolia T. & G. is a variable species of the southeastern coastal plain, and 
appears to be the most primitive species of the group in their evolution 
from the Angustifoliae. Although some of its variants approach V. con¬ 
cinna, it is generally distinguished by the broader, regularly imbricated 
involucre and the broad leaves. V. flaccidifolia Small is a well-marked 
species of the southern Appalachian region. V. altissima Nutt., the last 
species of the group, has a wide distribution from Georgia and Alabama 
north and west to New York and Missouri. Typical forms of the species 
avoid the coastal plain and are characteristic of the woodlands of the central 
states, but the variety laxa Gleason occurs along the Gulf Coast. In its 
western extension V. altissima comes in contact with several species of the 
western migration route, and many intermediate forms occur which are 
probably to be considered as hybrids. 
Considering the 35 species with paniculate inflorescence as a whole, we 
see that the species with primitive involucre invariably lie far to the south 
or southwest, and that those with the broadest and most obtuse scales, as 
well as those with the most filiform scales, lie always well to the north or 
northeast. It is also worthy of note that only seven of the 35 have attained 
a wide distribution, while the other 28 occupy small or localized ranges. 
These seven are V. fasciculata Michx., V. interior Small, V. missurica Raf., 
V. angustifolia Michx., V. glauca (L.) Willd., V. noveboracensis (L.) Michx., 
and V. altissima Nutt., representing six species-groups. This fact alone 
may indicate the comparatively recent immigration and incomplete evo¬ 
lution of the genus in the northern portion of its range. 
The general relations of the 63 species of the genus in which the bracteal 
leaves are suppressed is exhibited in a diagram (fig. 3). 
In the evolution of the genus in North America, no general plan or 
