TAXONOMY AND DISTRIBUTION OF ERIODICTYON 
LERoy ABRAMS AND FRANK J. SMILEY 
(WITH THREE FIGURES) 
In 1905, Chancellor JORDAN (7), in reviving the isolation theory, 
presented the following general law: ‘(Given any species in any 
region, the nearest related species is not likely to be found in the 
same region nor in a remote region, but in a neighboring district 
separated from the first by a barrier of some sort.” 
Botanists were not agreed as to the applicability of the law to 
plants, and Lioyp (8) even asserted that it ‘‘would be more in 
harmony with the facts in the case as understood by the botanists 
if stated in the converse form.”’ At the time we were inclined to 
accept the law and offered (1) a number of illustrations in support. 
But it was obvious that very few data on the distribution of plants 
in this country were available. Few attempts had been made to 
map accurately the distribution of closely related species. Distri- 
butional notes in the manuals were of such a general nature that 
they were largely useless for such a study, and many of the her- 
barium specimens were but little better, the average collector’s 
data being far too meager and often confusing. The need for care- 
ful distributional studies of closely related species seemed impera- 
tive, and with this in mind we have been collecting data on a 
number of Pacific Coast genera. 
Eriodictyon was selected as one of the genera for these distribu- 
tional studies for various reasons. The species constitute a single 
clearly defined natural group instead of an aggregate of groups, 
as is often the case with the larger genera; they are all evergreen 
shrubs readily detected in the field at all times of the year; and, 
finally, their center of distribution is in southern California, the 
region with which we are most familiar. 
As originally recognized by BENTHAM (2) and Gray (4) and as 
recently delimited by Branp (3), the genus Eriodictyon com- 
prises a small natural group of sclerophyllous shrubs peculiar to 
California and the Southwest, where they are commonly called 
115) [Botanical Gazette, vol. 60 
