Tropie and Subtropie Affinities. 319 
not only in their systematic relationships, present distribution in the region 
and probable past history, but even, to a considerable degree in their ecologic 
constitution. 
The first category includes plants of probable neotropic origin which 
have in all likelihood made their first appearance in the Appalachian region 
in geologically very modern times, probably after the close of the glacial 
period. The second category includes plants probably not of neotropic origin 
which are in several cases, probably the more or less modified descendants 
of the flora of later Eocene and Miocene times that extended to high 
FR 
& 
RK ” 
Pe N 
Fig. 13. Aamamelis virginiana L., witch hagel. An element of the deciduous forest formation 
of eastern North America from Nova Scotia to Texas, producing its flowers in early winter. 
After Die Natürlichen Pflanzenfamilien III 2a, p. 128—129. 
northern latitudes. The number of plants in this group occurring both in the 
coastal plain and in the Appalachian region is notably smaller than in the first 
group. Most ofthe species, as well, as many ofthe genera, comprised in this 
category are characteristic neither of tropic, or high northern regions. They 
belong in great part to groups which are most largely represented at present 
in the mountainous parts of the warm belt of the northern temperate zone, 
in both the eastern and western hemispheres. Some of them, however, are 
of floral types which are to-day most highly developed in the tropics, suc 
as the species of Arundinaria, Berchemia scandens, Cissus ampelopsis ( Ampe- 
lopsis cordata), Aralia spinosa and Symplocos tinctoria. Yet the groups to 
which several or all ofthese species belong, formerly had a much wider extra- 
tropic distribution than is now the case. 
