PDF - CES (IISc)

34 8
SYSTEMATIC
is different from every other, and is special to these southern regions. Dar-
bishire himself described 34 new Antarctic species, but only 10 of these
are from true Antarctica; the others were collected in South Georgia, the
Falkland Islands or Tierra del Fuego. Even though many species are
endemic in the south, the fact remains that a remarkable number of lichens
which occur intermediately on mountain summits are common to both Polar
areas.
C. LICHENS OF THE TEMPERATE ZONES
Regions outside the Polar Circles which enjoy, on the whole, cool moist
climates, are specially favourable to lichen growth, and the recorded numbers
are very large. The European countries are naturally those in which the
lichen flora is best known. Whereas polar and high Alpine species are
stunted in growth and often sterile, those in milder localities grow and fruit
well, and the more highly developed species are more frequent. Parmeliae,
Nephromae, Usneae and Ramalinae become prominent, especially in the
more northern districts. Many Arctic plants are represented on the higher
altitudes. A comparison has been made between the lichens of Greenland
and those of Germany: of 286 species recorded for the former country, 213
have been found in Germany, the largest number of species common to
both countries being crustaceous. Lindsay 1 considered that Greenland
lichens were even more akin to those of Scandinavia.
There is an astonishing similarity of lichens in the Temperate Zone all
round the world. Commenting on a list of Chicago lichens 2
by Calkins ,
Hue 3
pointed out that with the exception of a few endemic species they
resemble those of Normandy. The same result appears in Bruce Fink's 4
careful compilation of Minnesota lichens, which may be accepted as typical
of the Eastern and Middle States of North Temperate America. The
genera from that region number nearly 70, and only two of these, Omphalaria
and Heppia, are absent from our British Flora. The species naturally present
much greater diversity. Very few Graphideae are reported. In other States
of North America there occurs the singular aquatic lichen, Hydrothyria
venosa, nearly akin to Peltigera.
If we contrast American lichens with these collected in South Siberia
near Lake Baikal 5
, we recognize there also the influence of temperate
conditions. Several species of Usnea are listed, U. barbata, U. florida,
U. hirta and U. longissima, all of them also American forms, U. longissima
having been found in Wisconsin. Xanthoria parietina, an almost cosmo-
politan lichen, is absent from this district, and is not recorded from Minnesota.
The opinion 6 in America is that it is a maritime species: Tuckerman gives
1
2
Lindsay 1870.
Calkins 1896.
5 Wainio 1896.
3 * Hue 1898.
Fink 1903.
6 Comm. Heber Howe.