Affinities: Eastern Asia and North America. 317 
on a more northward line, although not so strikingly. If we compare the 
plants, say of New England and Pennsylvania with those of Oregon, and then 
with those of northeastern Asia, we shall find many of our own repeated in 
the latter, while only a small number of them can be traced along the route 
even so far asthe western slope of the Rocky Mountains. And these repetitions of 
east American types in Japan and neighboring districts are in all degrees of likeness. 
Sometimes, the one is indistinguishable from the other; sometimes, there is a 
difference of aspect, but hardly of tangible character; sometimes, the two would be 
termed marked varieties if they grew naturally in the same forest, or in the same 
region; sometimes, they are representative species, the one answering closely 
to the other, but with some differences regarded as specific; sometimes, the 
two are merely of the same genus, or not quite that, but of a single, or a 
very few species in each country. In the paper above cited by Asa Gray 
and also in the classic work of A. ENGLER, 1879 (see Bibliography page 47, 
vol. I. 22—43) a comparison is made by means of tables of-the floras of three 
widely separated regions, Atlantic North America, Pacific United States and 
north eastern Asia, Japan to Altai and Himalayas. Alpine plants on the one 
"hand, and subtropic plants on the other, are excluded, as also species which 
extend through Europe into north-eastern Asia, the object being to exhibit 
the peculiar relations of the floras of eastern North America and eastern 
temperate Asia. Only seven genera are peculiar to north-eastern Asia and 
north-western America: viz., Phellopterus (Glehnia), Fatsia (Oplopanax) and 
Lysichitum, each of a single species common to both coasts; Achlys, of whic 
there is a Japanese species said to differ from the American; Boschniakia, of 
a common high northern species, and a peculiar one to California; Zchenais 
(Cnicus) of one or two Asiatic species, one of them lately found in California 
and Colorado, but possibly of recent introduction; and Castanopsis, a rather 
large and characteristic east Asian genus, represented by a single, but very 
distinct, species in Oregon and California. 
4. Tropic and Subtropic Affinities. 
In addition to the European element and the element which shows relationship 
to the flora of eastern Asia, the flora of eastern North America has a very 
strong admixture of species which belong to the tropic and subtropic countries. 
Growing amid the very large body of Carolinian forms which characterize the 
lower slopes of the mountains and the valleys between there occurs a much 
smaller number of species which are most abundant in and characteristic of 
the austro-riparian area of the lower Austral climatic zone of some phyto- | 
geographers. Only two or three trees and a few shrubs, which are distinctly 
of the lower Austral zone, extend into the mountain region '). There is, how- 
ever, a respectable number of herbs, a hundred species and over, which, most 
I) KEARNEY, TuoMas H.: The lower austral Element in the Flora of the southern Appa- 
lachian Region. Science new ser. XII: 830—842. Nov. 30, 1900. 
