fANUARY, 1900. 
Bruncken — Distribution of Some Trees, etc. 
4.1 
is said to have been numerous on the east side of the ^lihvaukee 
river, and of which some individuals survived to within a few 
years on the river bank, about a mile above Lindwurm's. In the 
ravines leading from the upland to the lake beach, down the high 
clay banks at Whitefish Bay and Fox Point, is the only place in 
this region where the dwarf juniper (Jiuiiperus coiiiimiuis var. 
alpina) is found, a shrub very characteristic of the lake shore 
farther north, and especially on the Door County peninsula. Here 
also the Arbor Vitae is represented by a few scattering individuals. 
It may be significant, perhaps, that the stag horn sumach {Rhus 
hirta) is nowhere so abundant and vigorous as in this same local- 
ity. Although this species flourishes far to the South, its greatest 
development is reached in the North. If the search for charac- 
teristically northern plants were extended to the herbaceous vege- 
tation, it is very probable that many more species would l^e found 
in the region. Another peculiarity is the rarity of white oaks in 
the immediate vicinity of the lake. Here Qucrcns rubra is al: 
most the only oak, while in the other parts of our district the sev- 
eral species of white oak are far more frequent than On. rubra. 
In the northern part of the state, the latter species alone occurs of 
all the oaks. 
With the single exception of the yellow^ birch, all the northern 
plants mentioned occur only in the vicinity of the lake, some, like 
the juniper, only on its immediate shore. The conclusion appears 
therefore obvious that the influence of the lake has some- 
thing to do with giving a favorable station to these species which 
are excluded from the surrounding country. Just how this influ- 
ence is exerted, remains to be explained by exact observations. 
In a general way, it may be said that the local climate, so far as it 
affects vegetation, is modified in a two-fold manner: First, the 
maximum temperatures during the summer months are kept 
down ; secondly, the amount of evaporation is reduced. Hand in 
hand with this remarkable occurrence of northern species on the 
lake shore there goes a phenomenon which makes the situation 
still more interesting. 
The map prepared by the Biological Survey of the U. S. Agri- 
cultural Department places nearly the whole of Wisconsin w^ithin 
the Transition or Alleghanian life zone. But a strip aloncr the 
lake shore, stretching to about the latitude of Milwaukee, is placed 
within the Upper Austral, or Carolinian, zone. These zones are 
arranged according to faunal rather than floral characteristics, but 
if they are approximately correctly mapped, the faunal and floral 
zones should very nearly coincide. AVe find that interesting phe- 
nomenon, therefore, that along the lake shore are mingled both 
Northern and Southern life forms which do not occur in" this lati- 
