316 Part III. Chapter 4. 
The following plants, not found north of 48° in America, are not met with 
north of 55° in Europe: 
Myriophylium verticillatum L. | Najas flexilis Delile. 
Zannichellia palustris L. Ruppia maritima L. 
Vallisneria spiralis L. (Europe: 46°n.l.). ‚ Potamogeton compressus L 
Typha augustifolia L. » obtusifoliusMert.&Koch. 
Najas major All. Carex riparia Curt. 
The following ten species are all found in this country at least, as far Be 
as latitude 50° and few of them extend north of latitude 55° in Europe). 
Centunculus minimus L. 
Rumex maritimus L. 
Sagina procumbens Hook. 
Circaea lutetianaL. (Norvegia: 61°n.1.) 
Scrophularia nodosaL. (Norvegia: Se Carex muricata L. (Norvegia: 64°n. 1) 
Salsola Kali L. L » laevigata Sm. f 
Lythrum hyssopifolium M. A. ER | Hordeum pratense Huds. (= H. seca- 
(=L. alatum Pursh). linum Schreb.). 5 
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3. Eastern North America and Eastern Asia. 
Since Asa GRAY by a comparison of the elements of the flora of North 
America with those of other regions established the fact that the flora of 
eastern America is related to that of eastern Asia, his conclusions have been 
accepted as expressing a phytogeographic principle of wide application. This 
comparison”) will bring out the salient features of our flora. If we comp 
the United States with Japan, Manchuria and northern China, i. e. eastern. North 
America with eastern north Asia we find an astonishing similarity. The larger 
part of the genera of the castern region which are wanting in California are 
present in Japan, or Manchuria, along with other peculiar plants divided between 
the two. There are plants of the one region which have no representatives 
in the other. There are types which appear to have reached the Atlantic 
states from the south; and there is a larger infusion of subtropic Asiatic typ®® 
into temperate China and Japan; in the case of these there is no relationship : 
between the two countries. There is also, no small number of genera with 
some species which, being common all around or partiy around the northern 
temperate zone, have no special significance because of their occurrence in 
these two katipodal floras. The point to be made is, that many, or even 
most, of the genera and species which are peculiar to Atlantic North America 
as compared with Europe, and largely peculiar to Atlantic North America, 
as compared with the Californian region, are also represented in Japan 
Manchuria, either by identic or closely similar forms. The same rule holds 
ı) JAMES, JosEPH F.: On the geographical Distribution of the indigenous Plants of Europe 
and the northeast United States. Journal Cincinnati Society Natural History April 1887. 
2) GRAY, Asa: Presidential Address: Proceedings American Association for Advancement 
Seiencee. XXI: 1-31. “ 
