Le a 
Statistics of the Flora of the Northern States. 79 
to the floras of almost all the temperate regions of the world. 
Out of the 326 genera, 
284, or 87 per cent are diffused around the northern hemis- 
_ phere, or over the greater part of it; 
201, or 61 per cent, extend into the tropics or cross the equa- 
or, 
- 177, or considerably over half, are both widely diffused over 
the northern temperate zone and extend into or beyond the 
tropics :—leaving 
18, or only 54 per cent, as nearl peculiar to Eastern North 
America and to Europe; and very few even of these are 
strictly peculiar. 
A simple enumeration of them will show how trivial a part 
these 18 American-European genera play in the two floras. 
They are: 
Bellis, Fedi 
Cakile. Hottonia, 
Calla, Lipa 
Carpinus, Melampyrum, 
Cassandra, Narthecium, 
Cercis, Ostrya, 
Convallaria, Scheuchzeria, 
orema, Subularia, 
Dupontia, Waldsteinia. 
Most of these are very small genera, four if not five of them 
having only a single species each. Cercis cnet ai to 
California, and south to near the tropical line. ypontia is & 
purely arctic genus, to which our species, so called, is referred 
with much misgiving. . Hottonia is said to havea third species in 
Java, which would exclude it from the present list. Moreover, 
five of these genera are represented only by identical species. — 
€ ial resemblance of our flora to that of Europe, it is 
Clear, is not owing simply either to the large proportion of en 
era In Common, or to any thing striking or important har € 
genera nearly or quite peculiar to the two. The latter, in eed, 
are usignificant in our flora, and not to be compared, as to any 
Species, partly in the i 
in those whic closely answer to each | in the two floras. 
he citation of representative species, to be of much value, 
should be more critical than it generally is in such comparisons. 
the degrees of affinity should be classified as strictly as the sub- 
Ject admits of, under several heads; beginning with the plants 
80 closely related in each that they form a sort of limbo between 
