LICHEN DISTRIBUTION IN THE SANTA CRUZ PENIN- 
SULA, CALIFORNIA 
ALBERT W.C. T. HERRE 
The Santa Cruz peninsula, California, forms a rough triangle 
extending in a northwesterly direction from Monterey Bay on the 
south to the Golden Gate at the north, a distance of ninety miles or 
more. In breadth it varies from about thirty-five miles at the widest 
portion to perhaps six miles near the northern end. Laved on the 
west by the Pacific, its eastern boundary is formed by San Fran- 
cisco Bay and the broad, originally treeless Santa Clara—San Benito 
valley; while at the southeast the Pajaro cuts its way through the 
range and separates it from the Gabilan range. 
Rising from sea-level along most of its border, it reaches at its 
highest point an elevation of 3793 feet and embraces within its 
limits every variation between the dense, unbroken redwood forest 
and the bare, sea-girt rock, the cloud-swept mountain crag, and the 
vast expanse of monotonous salt marsh. 
Separated thus from the adjacent country and having such a 
diversified surface, it forms a natural biological region, well known 
both to the zoologist and the botanist. Though lichens are notorious 
for their wide geographical distribution, a study of the Santa Cruz 
lichens shows that they too are affected by the comparative isolation 
of the peninsula. 
In addition to its possession of a number of endemic forms, one 
of the most interesting features of the lichen flora of the Santa Cruz 
peninsula is the commingling of boreal or alpine, temperate, and 
tropical species. At the same time, there is a remarkable absence 
of certain lichens which we should naturally expect to find in the 
region. That no species of the genus Graphis should be found, and 
that Cladonia rangijerina and all forms of the genus Stereocaulon are 
absent, is an anomaly that as yet seems baffling, since forms ordi- 
narily associated with all these are common. 
But the mingling here of lichens typical of different phytogeo- 
graphical regions can be explained, I believe, by a study of the 
267] [Botanical Gazette, vol. 43 
